Semisolid creams and ointments containing 0.05% w/w clobetasol 17 propionate (CP) as active ingredient are categorized as superpotent topical dermatological corticosteroids. The objective of the study was to evaluate the content and transdermal delivery of CP from eleven commercial dosage forms, including three ointments and eight creams. It was found that the CP content of the ointments ranged from 77.5 to 96.1% of the labeled amount, and that of the creams ranged from 84.0 to 105.6%. In vitro transdermal flux of CP through nude mouse skin ranged from 0.156 to 0.270 μg/cm2/h for ointments, and 0.100 to 0.521 μg/cm2/h for creams. Total amount of CP penetrated in 8 h ranged from 1.03 to 1.75 μg for ointments, and 0.67 to 2.95 μg for creams. Lag time to reach steady-state of delivery ranged from 1.48 to 1.63 h for ointments, and 1.53 to 3.19 h for creams. In comparison with the brand name products, transdermal flux of CP from the generic ointments was 57.7% and 83.5% of Dermovate ointment, and that from the generic creams ranged from 19.2 to 94.8% of Dermovate cream. The results demonstrated that commercial 0.05% CP creams and ointments were highly variable in the transdermal delivery of CP, which may influence their bioavailability and clinical efficacy.