Background The epidemiology of contact dermatitis can be analyzed using clinical data from skin allergy units. Objectives The aims of this study were to define the profile of patients attending a skin allergy unit and to determine the prevalence of the most common sensitizations in this population. Material and methods Throughout 2008, a retrospective observational study was carried out in the 5 hospitals of the Spanish Surveillance System on Contact Allergies. All patients underwent skin patch tests with the Spanish standard series. The frequencies of sensitization were normalized for age and gender. Results Data were gathered on 1161 patients. The 5 allergens that gave the most frequent positive reactions were nickel sulfate (25.88%), potassium dichromate (5.31%), cobalt chloride (5.10%), fragrance blends (4.64%), and balsam of Peru (4.44%). The least frequently detected reactions were to quinolone–clioquinol mix and sesquiterpene lactone mix. There was a 35% prevalence of sensitization to nickel among women. Conclusions The profile of sensitizations in Spain is similar to that of other Southern European countries. Nickel sulfate continues to be the most prevalent allergen, particularly in women. The low prevalence of sensitization to quinolone–clioquinol mix and sesquiterpene lactone mix supports their exclusion of the Spanish series.