Objective: To assess patient compliance with a transdermal contraceptive and to compare rates of perfect compliance with a standard oral contraceptive. Design: Two multicenter open-label contraceptive efficacy studies conducted primarily in North America (Studies 002/004) were included in this compliance analysis. Healthy women 18-45 years of age were to be exposed for 6 or 13 cycles to the transdermal contraceptive (n = 1672) in Study 002 or randomized to the transdermal contraceptive (n = 812) or Triphasil® (n = 605) in Study 004. In both studies the transdermal contraceptive regimen was 3 consecutive 7-day patches (21 days) followed by 1 patch-free week per cycle. Thus patches were removed and replaced on the same day of the week. Triphasil® was administered according to the US physician package insert. Materials/Methods: Perfect compliance was defined as 21 consecutive days of drug-taking followed by a 7-day drug-free period; also for transdermal contraceptive users no patch could be worn for more than 7 days. Perfect compliance rates both overall and by age group (18-19 20-24 25-29 30-34 35-39 and >/= 40 years) were summarized. Transdermal contraceptive data from both studies were pooled for analysis; data from Study 004 were presented by treatment group. In Study 004 for purposes of statistical analyses a t test was used to compare the 2 treatment groups with regard to the overall proportion of each subjects’ cycles in which there was perfect compliance (the subject was the experimental unit). Results: In the pooled analysis the percentage of cycles with perfect compliance was 89.7% with the transdermal contraceptive; compliance rates were consistent across age. In Study 004 the percentage of cycles with perfect compliance was 88.7% with the transdermal contraceptive and 79.2% with Triphasil® (p < 0.001). Perfect compliance rates were similar across all age groups with the transdermal contraceptive but were reduced in younger subjects in the Triphasil® group. Conclusions: Compliance with the new ORTHO EVRA™ weekly dosing regimen is superior to compliance with Triphasil®. Compliance with ORTHO EVRA™ is unaffected by age whereas compliance with Triphasil® is lower in younger compared with older subjects. (authors)