The protein of silkworm pupae (PSP) has been thought to be a new available source of high quality protein that contains all the amino acids needed by the human body. The safety of PSP was evaluated systematically by a series of acute and sub-acute toxicological tests: (i) Acute toxicity test: The oral maximum tolerated dose of PSP was more than 15.0 g/kg body weight in mice, due to the absence of toxicity according to the criteria of acute toxic classifications; (ii) Mutagenicity test: PSP had no mutagenicity, as judged by a negative Ames test, mouse bone marrow cell micronucleus test and mouse sperm abnormality test; (iii) 30 days feeding study: No deaths or abnormal hematological, clinical chemical and histopathological changes and clinical signs had been found in rats when administrated PSP at 0.30, 0.75 and 1.50 g/kg/day to the rats for 30 days in each group during the test, respectively. No statistically significant differences had been found in body weights, food consumption and food efficiency of rats in each test group (P>0.05). These results indicate that PSP can be generally regarded as safe at a maximum dose of 1.50 g/kg/day in rats.