OBJECTIVES: The quality of dermatologic care provided by physician assistants has not been well documented. This study characterized the use of potentially inappropriate combination medication clotrimazole/betamethasone diproprionate (a proxy for potentially inappropriate care) by physician assistants compared to dermatologists and primary care physicians. METHODS: Data obtained from the National Ambulatory Medical Care Survey (1990-2000) were used to determine practitioner factors associated with a prescription for clotrimazole/betamethasone diproprionate. For each visit sampled that resulted in a dermatologic diagnosis, a patient log was completed to include demographic data, reasons for patient visits, physician diagnoses, services provided, and referral practices. For each year, we assessed patient visits to include twenty highest dermatology-related primary field diagnoses (using ICD-9 codes) at which clotrimazole/betamethasone diproprionate was mentioned. Practitioners were grouped as dermatologists, dermatology PAs, primary care providers, and primary care PAs, other specialty physicians and other specialty PAs. One-way ANOVA and multivariate logistic regression analyses using STATA 9.0 were tested the study objectives. RESULTS: PAs, regardless of specialty, were more than four times as likely (OR: 4.3, 95%CI: 0.7, 25.6) to prescribe clotrimazole/betamethasone diproprionate when they were the sole provider of care compared to when under direct supervision by a physician (OR: 1.8, 95%CI: 0.4, 8.0). Dermatology PAs prescribed clotrimazole/betamethasone diproprionate at a rate of 3.8%, compared to the PCP prescription rate of 4.9% and the dermatologist prescription rate of 0.2%. The highest rate of clotrimazole/betamethasone diproprionate prescription was seen in PAs practicing under PCPs, 16.9%. CONCLUSION: The quality of dermatologic care provided by dermatology physician assistants is closer to that of primary care physicians than that of dermatologists, evidencing a need for more extensive training for these practitioners. However, the use of closely supervised PAs may help provide more accessible and higher quality dermatologic care to all patients than provided by primary care practitioners.