Abstract.Irregular peaks ofP.falciparummalaria incidence were monitored in Suriname during 1982‐86. An attempt is made to correlate these fluctuations of malaria rates with rainfall and river level in relation to the periodic availability of breeding habitats for the malaria vectorAnopheles darlingiRoot.Densities of adult femaleAn. darlingiwere recorded in the Upper‐Marowijne region of Suriname, in a focus of malaria along the Marowijne River. Peaks in biting densities correlated well with periods of (i) high water level in the long rainy season, (ii) low water level in the long dry season, and (iii) abundant rainfall in the short rainy season. Critical levels of river‐height and rainfall were defined which could explain most of the monthly fluctuations in malaria parasite incidence observed in this