Abstract: Objective To explore the acute toxicity of DL-homocysteine to β cells. Methods Passage INS-1E cells were incubated in RPMI 1640 for 2 days,in Krebs-Ringer buffer（KRB） with 0.1% BSA for 30min,and then in modified KRB containing glucose and Hcy for 60min according to the protocol. The medium was collected for insulin assay. Female NMRI mice were anaesthetized with pentobarbital. Collagenase technique was used to obtain pancreatic islets which were handpicked under a stereomicroscope and kept in modified RPMI 1640 overnight at an atmosphere containing 95% humidified air and 5%CO₂. Then the islets were incubated in modified KRB with 0.1%BSA for 30min at 37℃,and then individually incubated at 37℃ for 60min in 100mL of modified KRB containing glucose and Hcy according to the protocol. The medium was collected for insulin assay. Results Hcy at 1 000mM decreased glucose-induced insulin secretion from INS-1E cells and mouse islets. Conclusion Hcy can inhibit insulin secretion from glucose-induced INS-1E cells and mouse islets.