The proposal that a parasitophorous 'duct' traverses the malaria-infected erythrocyte cytoplasm and is responsible for the unusual molecular uptake kinetics observed in malaria, has created considerable debate on the nature of macromolecular transport in this parasite. The existence of a 'duct' has important implications for the immunobiology of this parasite, particularly the possibility that antibodies may have access to 'internal' antigens in malaria. The most compelling evidence that there is a direct connection between the parasite and the surrounding media comes from the experiment of Pouvelle et al. (Nature 353, 73-75 (1991)) using small highly fluorescent latex spheres. However, we have found that fluorescent labeling of the parasite and tubular structures that extend from the parasite is due to the release of dye from the latex spheres during the incubation and is not due to the uptake of the spheres themselves. The inability of malaria-infected erythrocytes to take up latex beads down to 14 nm diameter establishes that an 'open' channel connecting the parasite with the surrounding media does not exist. This finding has important implications for establishing the unusual nature of macromolecular transport across the infected erythrocyte cytoplasm in malaria.