Brazil nut cake, a by-product of small scale oil extraction, is of potential use as a dry season feed supplement for cattle in North Eastern Bolivia. A survey indicated that over 800 tonnes/year of shelled Brazil nuts are used for oil extraction and cake production in Riberalta. Oil extraction plants were also surveyed and samples taken for the analysis of chemical composition, in vitro digestibility and aflatoxin contamination. The nut cakes varied in composition depending on the quality of the nut used and oil extraction process. Cakes had high residual oil contents (100 to 318 g/kg DM) and high protein contents (238 to 442 g/kg DM). Crude fibre contents ranged from 25 to 108 g/kg DM, the higher contents being related to the addition of rice hull in the extraction process. The cakes were highly digestible (69.6 to 94.4%), the lower digestibilities being related to rice hull inclusion. Brazil nut cakes were found to be rich sources of protein, phosphorus and sulphur amino acids. Brazil nut cakes produced from rotten nuts (black cakes) had relatively high levels of aflatoxins and could constitute a hazard to milk consumers if fed to dairy cattle.