The research was conducted to evaluate the safety of beef derived from human α-lactalbumin gene-modified cattle by 90-day feeding study in male and female Wistar rats.Methods Transgenic beef or conventional beef was processed into powder. Five percent of beef powder was incorporated into diet and other ingredients were adjusted to simulate AIN93G purified diets for laboratory rodents. Rats were randomly assigned into three groups with approximately similar initial mean body weights, which were transgenic beef group, conventional beef group, and AIN93G diet group. Clinical observations were conducted daily during the 90-day study, and body weight and food consumption were weighed weekly. At the end of the study, urinary examination, hematology and blood biochemistry examination, macroscopic and microscopic examinations were conducted. Results There were no biologically significant differences between the transgenic beef group and the conventional beef group in all items observed(P＞0.05).Conclusion The present 90-day feeding study suggested that transgenic beef might be as safe as conventional beef.