Experiments were conducted to investigate a possible interference by raw soybean meal (RSM) with B12 nutriture of chickens. In Experiment 1, day-old chicks were fed B12-free isonitrogenous and equienergetic diets containing 0 or 40% RSM to determine if RSM accelerated storage losses of B12. After 42 days, RSM decreased growth (P less than .01), decreased hepatic (P less than .01) and blood (P less than .05) concentrations of glutathione (GSH), and increased (P less than .01) pancreas and liver weights. However, statistically significant differences due to treatment were not detected in hepatic B12 concentration, indicating that RSM does not enhance B12 turnover in chicks. To ascertain the effect of RSM on B12 absorption, 9 micrograms B12/kg diet was added to diets containing 0 or 40% RSM and fed to chicks to 42 days of age. Raw soybean meal depressed growth (P less than .001) and hepatic GSH (P less than .01) and increased (P less than .001) pancreas weights. The RSM had no effect on hepatic B12 concentration, suggesting that RSM trypsin inhibition does not impair B12 absorption in chicks. A third experiment was designed to test the hypothesis that vitamin B12 stimulates egg production or feed intake of hens fed a diet with 27% RSM. Vitamin B12-depleted hens were fed RSM or heat-treated soybean meal (HSM) diets containing equivalent amounts of soybean protein, oil, and hulls. Hens received either 26 micrograms B12/kg BW per os or 13 micrograms B12/kg BW intramuscularly twice within a 30-day period.(ABSTRACT TRUNCATED AT 250 WORDS)