The growth of four Bacillus cereus strains producing diarrhoeal toxin at 32°C (F4433/73 and 29.155, isolated on the occasion of foodborne outbreaks, and F4581/76L and F4581/76R, two variants of a clinical strain), a weakly toxigenic strain isolated in routine analysis of food (3505M) and an emetic isolate (F3502/73) was investigated at low temperature. Biomass was determined by protein assay. Generation times were: for strain F3502/73, which grew at [ges ]12°C, 8·71 h (at 12°C); for other strains, which grew at [ges ]10°C, 10·2 to ∼18·9 h (at 10°C). Toxin production during growth was evaluated by a commercial kit (Oxoid) and by a toxicity test on Chinese hamster ovary cells. Strains F4433/73 and F4581/76, secreting high levels of diarrhoeal toxin during the exponential phase at 32°C, produced high levels of toxicity at 10°C until the stationary phase. Strain 29.155 had decreased toxin production at 10°C. Toxicities for cellular extracts remained low when compared with culture filtrates. A correlation was found between the toxicity values given by the two detection methods tested, and the suitability of both methods for the detection of potential poisoning isolates is discussed.