Background Allergic contact dermatitis (ACD) to topical medicaments is common. Medicaments are responsible for approximately 30% of all cases of ACD. The most common drugs associated with ACD include topically applied antibiotics, antiseptics, antihistamines, anesthetics, nonsteroidal antiinflammatory drugs, and corticosteroids. Certain body areas are particularly susceptible (ie, genital and perianal areas, ears, eyes, face and lower legs) Predisposing factors are: occlusion (skin folds, use of bandages), application in damaged skin (stasis dermatitis & leg ulcers, and other chronic dermatitis) and long-lasting use of multiple medicaments The aim of our study was to study the prevalence of ACD to topical medicaments in patients with suspected ACD attending the Unit of Allergy at the University Hospital in Montevideo. Methods 1175 consecutive patients; 781 F (63%) 394 M (37%) with suspected ACD were patch tested with the standard series and the topical medicament series, as well as other allergens according to the clinical situation. Results The most frequent allergens were: Neomycin (7.1%), Thiomersal (3.8%), Benzocaine (1.9%), Bacitracin (1.9%), Propolis (1.5%), Gentamycin (1.2%), Tixocortol (1.1%) and Budesonide 24 (0.8%). Conclusions Contact allergy to topical medicaments is common in patients studied by a suspected ACD in Uruguay. In these cases the topical medicaments that the patient is using should be included when patch testing.