A profile of referrals can help to define the characteristics of a physician's practice. Self-reported referral patterns in the practices of Family/General Practitioners (FP/GP), Internists (IM), and Obstetricians/Gynecologists (OB/GYN) in Maryland were assessed with a questionnaire mailed to an area sample of 1,715 physicians. A 65% response rate was obtained after three mailings (weighted N = 1,487). Self-reported referrals received per month averaged 16% of patients seen (six percent FP/GP, 13% OB/GYN, 23% IM), and were more frequent among self-employed, younger, metropolitan and female physicians who spent less time in patient care. Self-reported referrals made per month averaged ten percent (10% FP/GP), 11% IM, and eight percent OB/GYN), and were higher for physicians in metropolitan areas. The correlation between percentage referrals received and percentage referrals made was r = .19 (r = .03 FP/GP, r = .21 IM, r = .25 OB/GYN). Self-reported practice referral patterns are similar to referrals reported in prior studies, and can be used to consider specialty differences in referral behavior of physicians.