One hundred and fourteen strains of Bacillus cereus were isolated during presumptive plate-counts from 18 groups of industrialized, non-industrialized, crude or cooked food, belonging to 10 separate classes. Specific presumptive counts ranged from 10[raised to the power of 2] to 6 X 10[raised to the power of 3]/g or ml. Among these isolates, 13 strains were derived from 3 outbreaks of food poisoning (involving a minimum of 57 people), as determined by the assayed bacteriological quality of the ingested foods. As an adopted procedure to correlate toxicity and ability to promote illness in man, culture fluids of all strains were assayed to determine their ability to increase vascular permeability (APC) to cause necrosis in rabbits skin and to kill albino mice. APC was positive in 86.85% of the 114 strains, death of albino mice occurred in 65.79% and a combination of APC and death was observed in 59.65%. APC plus necrosis, or only necrosis, occurred with 34.21% of the culture fluids. Death, APC and death with or without necrosis, were demonstrated in the strains implicated with illness. This confirmed the known individuality of action exhibited by certain B. cereus food-borne toxigenic factors. The low presumptive counts of this bacterium in the order of 10[raised to the power of 2]-10[raised to the power of 3]/g or ml found in food, implicated or not with illness, suggests that the recommended number of B. cereus per g or ml of food sample should be reevaluated in our country. Furthermore, a wider range of food should be brought under bacteriological sanitary control for this species.