Topical corticosteroids are increasingly recognized as relatively common contact sensitizers. Between July 1988 and December 1991 2687 patients undergoing routine patch testing were also tested with tixocortol pivalate (TP). Over the same time period 528 patients were selected for testing with a series of 18 steroids. One-hundred and thirty-one cases (4.9%) of corticosteroid hypersensitivity were detected and 119 (90.8%) of these cases were positive to TP. Thirty-seven patients reacted to one or more steroids in the steroid series, the most frequent sensitizers being hydrocortisone, budesonide (3.6%) and hydrocortisone 17-butyrate (2.5%). Of these 37 cases, 20 (54%) reacted to more than one steroid simultaneously, but the patterns of cross-reaction were not consistent with previously suggested groupings. Screening for steroid allergy should be performed as part of standard patch testing. The value of TP as a marker of corticosteroid hypersensitivity is reinforced by this study, but no satisfactory marker was found for the 9.2% of cases not detected by TP. There remains a need for further markers of corticosteroid hypersensitivity. A prevalence of 4.9% of corticosteroid allergy amongst our patients suggests that the frequency of this finding is generally underestimated.