A total of 2057 children aged <10 years were selected at random from a demographic surveillance system and enrolled in 4 malariometric cross-sectional surveys in different seasons in Manhiça district in southern Mozambique. Plasmodium falciparum accounted for 90% of all malaria infections and the prevalence of asexual P. falciparum ranged from 13.7-21.7% at the end of the dry season to 30.5-34.0% at the end of rainy season. In order to determine the malaria attributable fraction (MAF) of fever, 1021 children from a nearby hospital acted as fever cases and from this separate case-control study the crude MAF was 36%, showing a marked age dependency. Plasmodium falciparum is the most common malaria species in Manhiça. This malaria-mesoendemic area has year-round transmission. The importance of other non-malarial fever-causing conditions among infants was highlighted. Malaria appeared to be a major contributory factor to anaemia in the area