Several types of diaper dermatitis are discussed: generic diaper dermatitis is most common and involves a simple erythema and mild scaling of the gluteal crease, buttocks, thighs, and lower abdomen. Candidal diaper dermatitis involves clinically significant infection with Candida albicans and presents as a sharply marginated area of erythema with significant involvement of the anterior thighs, genital creases, abdomen, and genitalia. Noduloulcerative diaper dermatitis may develop in a small percentage of patients who have chronic diaper dermatitis, as large, raised erosions with rolled margins. The lesions are most noticeable on the prominent body parts-genitalia, abdomen, thighs, and buttocks. Infantile seborrheic dermatitis involves a distinctive pattern of inflammation that usually begins beneath the diaper as a sharply marginated area of erythema with satellite lesions. Within 1-2 weeks, lesions develop on the scalp, cheeks, arms, legs, and intertriginous parts of the body. Impetigo is common in the diaper area, particularly in the first 6 months of life and during the warmer summer season. The lesions are usually bullous and represent infection by Staphylococcus aureus. Folliculitis appears as small, perifollicular erythematous papules and pustules, usually on the buttocks, thigh and lower abdomen. It is common in the warm summer months and is usually caused by bacteria such as S. aureus. Intertrigo categorizes disease that does not fit into the above categories. Often the patient presents with simple erythema of the folds without pustules or induration. This probably represents irritation and low-grade infection. It is important for the clinician to be aware that many other diseases can have manifestations in the diaper area.(ABSTRACT TRUNCATED AT 250 WORDS)