The providers at East Valley Internal Medicine strive to provide compassionate, comprehensive care for all patients. Our well-trained group of providers has a combined 120 years of experience. All provide women’s and men’s health care. Some have specific areas of expertise.

Mark Walmer, MD

specialty: Internal medicine and Addiction medicine

Dr. Mark Walmer is board certified in internal medicine. He is the founder of East Valley Internal Medicine and has been practicing since 1984. He specializes in addiction medicine, preventative medicine, hypertension, hypercholesterolemia, and diabetes. Dr. Walmer earned his medical degree from the Medical University of South Carolina in Charleston, South Carolina. He completed his residency at St. Joseph’s Hospital and Medical Center in Phoenix, Arizona. He is the president and medical director of East Valley Internal Medicine.

When Dr. Walmer isn’t treating patients he likes to spend time with his family traveling, swimming and riding bikes.   Dr. Walmer is also a huge baseball fan but especially the Arizona Diamondbacks!

Christina Zimmerman, MSN, NP-C

specialty: Internal Medicine, Women’s Health, Preventative Medicine, Longevity Care

Christina is a board-certified nurse practitioner and has been practicing medicine since 2009. She completed her undergraduate studies in nursing and earned her master’s degree at the University of Arizona in Tucson, Arizona.

When Christina isn’t at the office treating patients, she enjoys spending time with her young son and staying physically fit.

April Rosscup, MSN, FNP-C

specialty: Internal Medicine, Family Practice,  Preventative  Medicine,  Addiction  Medicine

April is a board certified nurse practitioner and has been in the medical field since 2016.  She completed both her BSN and MSN at Chamberlain University in Phoenix, Arizona.  Prior to becoming a Nurse Practitioner, April honorably served our country in the United States Air Force for 6 years.

On April’s time away from the practice she enjoys spending time with her family traveling and enjoying the outdoors.  She is also a Phoenix Suns SUPER FAN!

Robert Halligan, MD

specialty: Addiction Medicine
Dr. Robert Halligan is board certified in internal medicine and addiction medicine has been practicing since 1994. Dr. Robert Halligan earned his medical degree from Creighton University School of Medicine in Omaha, Nebraska. He completed an internship and residency at Good Samaritan Regional Medical Center in Phoenix, Arizona.

Dr. Halligan enjoys spending time with his family and many outdoor activities such as running, cycling, golfing and skiing.

Boris Schwartz, NP

specialty: Pain Medicine

New Provider Coming Soon

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