BACKGROUND: This study aims to evaluate the association between environmental and socio-economic conditions with asthma prevalence in the eight ISAAC centres in North-East Brazil. METHODS: Estimates on occurrence, severity and medical diagnoses of asthma in the previous 12 months were compared using environmental and socioeconomic indicators. Associations were assessed using simple linear regression and Pearson correlation coefficient. RESULTS: There was no difference in asthma prevalence between centres. Active asthma prevalence increased with increasing water privation, and this would explain 62 % of the observed prevalence. Median temperature increase was inversely related to active asthma (rEuro Surveillance (Bulletin Europeen Sur Les Maladies Transmissibles; European Communicable Disease Bulletin)0.81; p<0.05). There was a positive association between latitude and active asthma prevalence (rEuro Surveillance (Bulletin Europeen Sur Les Maladies Transmissibles; European Communicable Disease Bulletin)0.82; p<0.005), a negative association between severe asthma and yearly medium temperature (rEuro Surveillance (Bulletin Europeen Sur Les Maladies Transmissibles; European Communicable Disease Bulletin)-0.89; p<0.05), and a positive association with latitude (rEuro Surveillance (Bulletin Europeen Sur Les Maladies Transmissibles; European Communicable Disease Bulletin)0.78; p<0.05). CONCLUSION: Relation between the tropical weather and high prevalence of asthma was not confirmed. There were associations with water privation and latitude.