The abilities of potential chemoprotectants to inhibit cytotoxicity of ricin have been determined in vitro, using the macrophage cell line J744A.1. Six compounds were tested: alpha- and beta-galactopyranosylamine; N-bromoacetyl-alpha-D-galactopyranosylamine; N-bromoacetyl-beta-D-galactopyranosylamine; N-bromoacetylglucopyranosylamine; and N-bromoacetylmannopyranosylamine. Of the six compounds which were tested, only N-bromoacetyl-alpha-D-galactopyranosylamine and N-bromoacetyl-beta-D-galactopyranosylamine exhibited significant activity against ricin toxicity, as indicated by the release of lactate dehydrogenase (LDH) and aspartate aminotransferase (AST). The alpha-isomer provided greater protection against ricin toxicity and also exhibited less inherent cytotoxicity in the absence of ricin, as compared to the beta-isomer. Neither the alpha- and beta-galactopyranosylamines nor the glucose and mannose analogs were promising as potential chemoprotectants.