OBJECTIVE A prospective study was conducted to assess the evolution of the incidence of type 1 diabetes mellitus (insulin-dependent) in Málaga among children less than 14 years of age between 1982 and 1993. PATIENTS AND METHODS The capture-recapture method was chosen for estimating the probability of ascertainment and two sources were used: The hospital registry and Málaga Diabetes Association members. RESULTS We detected 437 children and the ascertainment achieved was 98.8%. The average annual incidence was 14.3/10(5) and the prevalence at the end of the period was 0.78 patients/10(3). During the last 6 years of the observation period, the incidence rose by 42%. The highest incidence was found among children between 10 and 13 years of age in both sexes. The age of onset and female/male ratio increased during the study period. There was an inverse relationship with monthly temperature. CONCLUSIONS In comparison with other European epidemiological studies, we found a higher incidence and increased rate of growth of the incidence of type 1 diabetes mellitus during the observation period.