Background: The silkworm powder from Japanese and Korean races has a high biological activity. However, there was less scientific evidence regarding bioactivities in Thai silkworm races. Objective: This research was interested in toxicity and antioxidant activities of Thai silkworm races. Material and methods: The 5th instar, 3rd day of growth stage of Thai traditional silkworm (Nanglai, Nangnoi and Samrong races) were lyophilized by freeze dryer and ground as silkworm powder. The acute and sub-acute toxicities studies were carried out in male Wistar rats. The antioxidant capacities of silkworm powder were investigated with DPPH, ABTS and FRAP methods. Results: The acute toxicity in rats by single dose oral administration show that the high dose at a concentration of 2,000 mg/kg b.w. did not have toxicity in rats. The sub-acute toxicity in rats by oral administration showed that the high dose concentration at 2,000 mg/kg body weight for 6 weeks had no toxicity in all group either. In addition, the hematological parameters and lipid profiles of treated group and control groups were not significantly different. The antioxidant study showed that silkworm powders were not significant difference in all groups of samples in three assays (DPPH, ABTS and FRAP). However, significant difference had been found in comparison to ascorbic acid (p < 0.05). Conclusion: Silkworm powder from three races of Thai silkworm did not produce any toxicity in male rats. In addition, the silkworm powder also exhibited antioxidant activities.