Perfusion organ culture of the trabecular meshwork was used to study the phagocytic ability of human trabecular cells. Cultured eyes were challenged with blood, latex microspheres, or zymosan particles for periods of 1 hour to 7 days. Trabecular cells were capable of ingesting all three types of particles. The presence of a foreign particle did not necessarily induce a phagocytic response, however, as free particles were seen in the intertrabecular spaces and Schlemm's canal. In contrast to studies in animals which indicate trabecular cell migration from the eye may play a role in the removal of foreign debris, limited human trabecular cell migration was observed. The effect of the culture process on trabecular cell phagocytosis was also studied, using adult cats. One eye received a phagocytic challenge in vivo with the fellow eye later receiving the phagocytic challenge in vitro. Phagocytosis was demonstrated in each eye, although more cells were involved with phagocytosis in vivo. The additional cells involved in vivo may have been recruited by an accompanying inflammation. Organ culture of human trabecular meshwork may be useful in the study of trabecular cell phagocytosis, and it allows separation of the effects of inflammation from the potential effects of phagocytosis itself.