Dr. Roy Kaplan has been in rheumatology practice for over 35 years specializing in rheumatoid arthritis, psoriatic arthritis, reactive arthritis, and ankylosing spondylitis, as well as the connective tissue diseases, including lupus, scleroderma, dermatomyositis, and polymyositis, and the vasculitis diseases, giant cell arteritis and polymyalgia rheumatica. His interests extend to osteoporosis, gout, and osteoarthritis.

He is a founding member of the American Rheumatism Association (now the American College of Rheumatology) and currently is a board member of the California Rheumatology Alliance. Dr. Kaplan especially enjoys teaching and sharing the clinical aspects of rheumatologic conditions with his non-rheumatology and rheumatology colleagues alike.