The aim of this study was to investigate the formaldehyde content of topical corticosteroid preparations available on the Swedish market. 73 samples were analysed with the chromotropic acid (CA) method for semi-quantitative formaldehyde determination and 30 samples with a high-performance liquid chromatographic method. These included 24 ointments, 28 creams, 1 lotion, 6 liniments, 2 gels, 9 solutions, 2 mousses and 1 oral paste. Formaldehyde was found in 5 creams and 1 ointment. Sources of formaldehyde in these preparations were discussed. Isopropanol was identified as a probable source of yellow discoloration, leading to false-negative results with the CA method.