In 2002, 945 patients (241 men and 704 women) were tested with the basic allergen set in three dermatology clinics providing diagnostic contact allergy service for Prague referal area. The authors evaluated only substances with possible relationship to contact allergy to cosmetic products. From the total of 945 patients, 173 (18.3%) - 42 men (17.4% of the total number of tested men) and 131 women (18.6% of the total number of tested women) - reacted to at least one selected substance. The most common hypersensitivities represented mixture of fragrances (74 positivities - i.e. 7.8% of tested), peru balsam (52 positivities - i.e. 5.5% of tested), lanolin (36 positivities - i.e. 3.8% of tested), formaldehyde (22 positivities - i.e. 2.3% of tested), colophony (18 positivities - i.e. 1.9% of tested), 5-chloro-2-methyl-4-isothiasoline-3-one + 2-methyl4-isothiasoline-3-one (MCI/MI) (9 positivities - i.e. 0.95% of tested), quaternium 15 (8 positivities - i.e. 0.85% of tested) and parabens (7 positivities - i.e. 0.74% of tested). These findings demonstrate, that the most common origin of sensibilisation in cosmetic products are fragrances and conservants. Relatively frequent positive reaction to lanolin can be explained by sensibilisation secondary to application of topical remedies - ointments and creams - containing lanolin. The sensibilisation to cosmetics correlates closely with an exposition rate. Cosmetics producers use time proven formulas, but there are also newly appearing substances, which, with large extent of use, can become significant for contact allergy development. As safe, according the literature data concerning the cosmetic conservants reactions monitoring, are considered only those substances to which hypersensitivity does not exceed 1%; contact allergy in 2% of tested is considered alarming and values over 3%, as a rule, mean serious problem.

        Key words: contact allergy - cosmetics - european standard allergen set