Our Doctors

All professionals at ADA Adult Medicine Clinic maintain the highest levels of accreditation and pursue ongoing education to stay abreast of the latest trends in the medical field. Read on to learn more about our staff's experience and training.



Bruce W. Dennis, M.D.

Dr. Dennis moved to Ada Oklahoma in 1995 after completing his residency in Internal Medicine at the University of Oklahoma.  He is a graduate of Norman High School, Abilene Christian University, and OU College of Medicine.  He has been married to his wife Sheri since 1988 and together they have four children.  Dr. Dennis is an outdoorsman and enjoys ranching, hunting and fishing.  He is an elder for Fittstown Church of Christ and has done relief work in Haiti since 2000.  


Holly K (Dennis) Farrar, APRN-CNP

Holly has joined our office and is now accepting new patients! She is an Ada HS grad and received her BSN from Oklahoma Christian University. She worked for Stephenson Cancer Center in OKC and completed the Family Nurse Practitioner program at Harding University School of Nursing before moving back to Ada.

She is married to Casey Farrar and they are proud parents of Dr. Dennis' super-cute grandson, Hudson Mark Farrar.


Joshua Corley, PA-C, MPAS

Joshua D. Corley, P.A. -C, Master of Health Science as Physician Associate Degree from the University of Oklahoma Health Science Center, Bachelor of Science in Biology from East Central University, certified in BLS, ACLS.

Haley Mitchell, APRN-CNP

Haley graduated from the RN program at Spring Arbor University after working for six years as a registered nurse primarily in emergency medicine. She is currently working at Ada Adult Medicine Clinic as a Nuse Practitioner. She currently lives in Goldsby, Oklahoma with her husband, two sons, and countless animals.





Michel Cosby, A.P.R.N.

Michel Cosby, A.P.R.N., graduated from Maryville University with a Master of Science in Nursing, Family Nurse Practitioner, Bachelor in Science, Major in Nursing from East Central University certified in ACLS, and BLS. 




Mandy Waters, APRN-CNP

Mandy Waters, APRN-CNP, graduated from Maryville University with a Master of Science in Nursing-FNP,  Bachelor of Science in Nursing, from East Central University, certified in ACLS, BLS, PALS, and TNCC. Mandy is married to Jerod Waters and they have two daughters who keep them busy with a lot of activities and sports. Mandy has lived in this area most of her life and enjoys caring for patients in her hometown.