Attraction of lung macrophages to particle deposition sites has been demonstrated in different animal species. We reported a threefold increase of the number of macrophages to occur within 40 min after polystyrene particle deposition in hamster airways [Geiser et al. (1994) Am. J. Respir. Cell Mol. Biol. 160: 594-603]. Complement-derived chemotactic activity is one of the mechanisms postulated for macrophage recruitment. It was the aim of this study to test whether complement-derived chemotactic activity is involved in the rapid recruitment of macrophages to the site of deposited polystyrene particles in hamster airways. We first developed an in vitro cell migration assay for hamster macrophages to assess complement-derived chemotaxis. Second, the bronchoalveolar lavage fluids (BALF) of four hamsters that had inhaled aerosols of polystyrene microspheres were tested for chemotactic activity by this bioassay and compared with BALF of four sham-exposed hamsters. Chemotactic response of macrophages was found toward complement-activated hamster serum, whereas macrophage migration was not increased toward BALF of particle and sham-exposed hamsters. In contrast, macrophage migration to BALF of both groups was reduced by 1.6-fold. Thus, the stimulus for macrophage recruitment to the site of deposited polystyrene particles in hamster airways could not be demonstrated using this bioassay.