Dr. William Sim, MD

I had a horrible experience with this doctor didn’t listen to all of my concerns and rushed the appointment when I wasn’t done. He didn’t make any sense when I asked about vitamins telling me he doesn’t believe in them but tells me to take magnesium.

I have been seeing Dr Sim for 5 years now after not being happy with my previous PCP. Dr. Sim was very attentive and immediately suspected and appendicitis and sent me to ER and it sure was, I had an emergency surgery. I most cases he has provided an accurate diagnosis, lab work as needed and any other test. He is very thorough and passionate.

I have been seeing Dr. Sim for about 8 years now and he is an amazing primary doctor. I had really bad time with my previous doctor and I had several health issues that I did not have figured out when I started seeing Dr. Sim. He has always listened to my symptoms and run tests to really try and get to the root of what's going on. He also will call with your test results so you don't have to worry about having to go back in every time he orders a test. Even recently when I had more symptoms pop up instead of just saying they are probably due to my multiple health conditions he sent me for more testing and even a 2nd opinion when he thought the rheumatologist may have over looked a possible condition that my symptoms and test results aligned with. I'm truly grateful to have found Dr. Sim and know that he is committed to his patients health & you can tell he keeps up with research and is very knowledgeable even on newer conditions. Also, Kathy at his office is so helpful with referrals.

Very attentive to patient's needs. Been our family doctor for 20 years. Takes time to listen to your concerns and takes time to explain things to you. Makes great referrals when needed.

I was referred by 2 existing patients of Dr Sim. I'm very picky and like to research any person or thing that I come into contact with beforehand. After 2 appointments and 1 call back from the doctor, I can comfortably give my positive recommendation if you're looking for someone. So far I have been seen on time and received calls back promptly. Support staff has all been friendly and professional.

After being misdiagnosed at another facility my husband said for me to go to his personal physician Dr Sim. Dr Sim instantly recognized the misdiagnosis and admitted me to emergency and saved my life. I am forever grateful for his attention to detail, his professionalism and his care. I highly recommend Dr Sim for anyone look for a great gastro physician

Dr Sim has been my personal physician for over 25+ years. There is no other physician I trust for my care. He is knowledgeable, professional and has always gone above and beyond for me and my family. His personal touch as well as the safe environment he creates are unparalleled. For anyone who is looking for a Gastro Dr I highly recommend Dr sim.

Dr. Sim is a true professional, and has been very helpful to me. I would recommend him without reservation to anyone in need of a kind, thoughtful and talented doctor.

I’ve visited several Doctors in the area and overall Dr. Simm is by far the best. He spends adequate time with you so you don’t feel rushed out.

Doctor was nice but one of staff was really stupid

I have been one of Dr. Sim's patients since his very early days in Downey. In this time, I have had several illnesses and surgeries. One illness was quite mysterious and I was sick for three months. Dr. Sim understood my anxiety. He worked the problem backwards - from most likely to least likely. He kept working until he found the answers. He is a doctor who will work with you. He is a doctor who returns your calls - sometimes within minutes. He explains and he listens.

Dr. Sim has been my doctor for the past 8-10 years. He has been great. Always there to take care of me. I am really glad I found him and his office. I most appreciate the walk-in appointments I am almost always able to make.

I was very impressed with Dr. Sim. My husband had been seeing another doctor who diagnosed him with COPD and gave an inhaler, but as symptoms got worse, the doctor just gave him another inhaler. I knew something was more serious so I changed his primary care physician to Dr. Sim. We came into his office on a Monday, January 2016. Dr. Sim knew immediately that my husband was very sick. He ordered some tests and by Friday my husband was admitted into the hospital. That is what I call thorough.

Dr Sim is very caring and professional. He listens to you and knows exactly how to care for you. He was recommended to me by a friend and best Dr I have ever had. Thank you Dr Sim for being my Doctor.

Dr. Sim put my dad in a skilled nursing home for muscle weakness. One day during his 3rd week there, my dad became very disoriented & was breathing too fast. I complained to the nurse & she informed Dr. Sim of my concern. Sim had her tell me that the reason it looked like my dad was breathing too fast was because he was so skinny. I knew that was not the case & continued to complain & call Sim's office, but I was ignored & nothing was done to help my dad. He died of sepsis 6 days later.

Dr. Sim is the best Dr. I've ever been to. He saved the life of my sister-in-law. I can't recommend him enough. He knows when to send you to a specialist and refers you to some of the best Drs. in their field.

Dr Sim is amazing. I moved out of the state so I had to leave him but he has been my doctor for 10 years. I recommend him to EVERYONE and not one has told me they didn't like him. HIs staff is wonderful and he is very attentive. I couldn't ask for a better doctor!!!

At first I thought Dr. Sim to be a great doctor, until my last visit when I was voicing my concern to him and he decided to bolt out of the room, telling me that hes too busy, and that he answers one concern a day for each patient, lets talk next time. What?!?! I could have a serious condition and you go off being unprofessional like that? Shows how much he cares for his patients and their health!!!