The toxicities of ROUNDUP and its component chemicals, glyphosate (N-phosphonomethylglycine) and polyoxyethyleneamine (POEA), were determined at 0, 1, 3, 6 and 24 h following administration to rats. The intratracheal administration of glyphosate (0.2 g/kg), POEA (0.1 g/kg), a mixture of glyphosate (0.2 g/kg) + POEA (0.1 g/kg), or ROUNDUP (containing 0.2 g/kg glyphosate and 0.1 g/kg POEA) elicited immediate respiratory effects which were more severe and which lasted longer in the groups receiving the POEA-containing preparations than in the glyphosate alone group. By 1 h, all test preparations had caused deaths, but more occurred from the POEA-containing preparations than from glyphosate. The po administration of POEA (1 g/kg), the mixture of glyphosate (2 g/kg) +POEA (1 g/kg), or ROUNDUP (containing 2 g/kg glyphosate and 1 g/kg POEA) produced diarrhea and blood-stained weeping from noses. Death was only seen from POEA at 24 h. Glyphosate (2 g/kg po) produced transient diarrhea without nose bleeds; POEA caused diarrhea at 1 h; and the mixture of POEA + glyphosate produced diarrhea later that increased in severity with time. Bloody nose secretions were seen only with the preparations that contained POEA. No deaths, respiratory effects or bloody nose secretions occurred in controls given saline. Both POEA and glyphosate caused lung hemorrhages and lung epithelial cell damage with po or intratracheal exposures. These results indicate POEA and preparations that contained POEA were more toxic than glyphosate.