Genetic analysis of olfC provides evidence for a role for integrins in the development and/or function of the olfactory system of Drosophila. The olfC gene was identified on the basis of mutations that result in specific defects in behavioural responses to acetate esters, and has been mapped to the cytogenetic interval 7D1;D5-6 on the X chromosome. The myospheroid (mys) gene maps to this region and encodes a beta subunit of integrins. Integrins are alpha(beta) heterodimers which are present on the cell surface and have been implicated in a variety of signalling roles. Mutations in mys fail to complement the olfactory deficits of olfC mutants. These defects can be rescued by misexpression of the mys+ gene under control of a hsp70 promoter. Mutations that affect the alpha subunit of the position-specific integrin PS2 show a dominant interaction with olfC. These results suggest that olfC is allelic to mys and functions together with alphaPS2 integrins in the olfactory pathway in Drosophila.