Background and Objective: Diarrhoeal is one of the principal causes of childhood morbidity and mortality in developing countries. It causes 2 million deaths in children every year and is the major cause of childhood hospitalization. Increase of diarrhoeal diseases are linked to ambient temperature as well as contamination of groundwater-fed water supplies after rainfall events, therefore it is important to estimate whether future projections of climate change will induce the increase of cases of this disease. The objective of this study is to project the future incidence of Diarrhoeal disease under a climate change scenario. Methods: Climate change projections were generated by ECHAM general circulation climate model under A2 scenario assuming emissions in 550 ppm CO2 by 2030. The excess of diarrhoeal diseases cases was estimated under this climate change scenario using (1) the average annual rate from 1998 to 2005; (2) literature base associating the increase of 5 percent of diarrhoeal cases with the increase of every degree C of temperature and 10 mm of precipitation; and (3) the projected number of diarrhoeal cases per 100000 inhabitants to 2030. Results: ECHAM A2 climate change scenario to 2030 is projected to increase the numbers of diarrhoeal cases by 5-12 percent. Most of the increase of cases is presented in the in coastal areas during the months of June, July, August and September. July and September are projected to be the months with higher increase of precipitation, but not with higher increase of temperature. Conclusion: Climate change is projected to increase the numbers of diarrhoeal cases and changes in precipitation are relevant to the results. Although some estimates of this disease have been calculated, these estimates need to be adjusted by other factors that influences over the disease and using more climate change scenarios.