Ten thousand new patients were seen between January 1971 and January 1975 at the Department of Pediatric Dermatology, "Hospital del Niño IMAN" in Mexico City. The patients were between 0 and 18 years old. They represented 10.4% of the entire pediatric population attending the general out-patient clinic of the hospital. The results of our study showed no significant difference among the sexes of patients. The highest proportion of patients in the sample were under one year of age. The most frequently observed groups of dermatoses were: parasitic, cutaneous reactions, viral and bacterial. The ten diseases most frequently observed were: papular urticaria (16.3%); atopic dermatitis (12.9%); scabies (10.4%); viral warts (8.4%); impetigo (6.8%); pitiriasis alba (6.6%); vitiligo (2.6%); acne (2.5%); dermatophytosis (2.4%) and numular eczema (2.3%). The 20 skin diseases most frequently recorded accounted for 85.8% of the sample. The ten most frequent skin diseases in each group of age were also recorded. The monthly and annual frequency for the more frequent dermatoses was studied. The present study provides epidemiological information for a rational development of programs on care, education and investigation in pediatric dermatology in Mexico.