Haemoparasitic infections in wild birds have been widely studied in order to understand parasite-host relationships, but our understanding of their impact on the host's fitness is still limited. In this study, we quantified the associations between microfilarial infections and body mass and between microfilarial infections and haematocrit values in Village Weavers Ploceus cucullatus. We screened blood samples (thin smear and buffy coat) for the presence of haemoparasitic infections and measured haematocrit values. Fifty-seven percent of 91 individuals screened carried a microfilarial infection but, contrary to expectations, no other haemoparasitic infections were detected in the blood samples. We found a negative relationship between microfilarial infection status and body mass, but no relationship between infection status and haematocrit values. Our results suggest that microfilarial infections may be associated with body mass loss in wild birds.