The incidence of avulsion fracture of ischial tuberosity is reported to present in 1.4%-4% of hamstring injuries. The injury mechanism is known to be caused by a sudden forceful hip flexion in the extended knee with eccentric load to the hamstrings. Although the majority of hamstring injuries are strains of the muscle, avulsion fracture of ischial tuberosity occurs rarely. In this report, a 13-year-old boy with avulsion fracture of ischial tuberosity is presented. Successful clinical outcome was achieved with careful conservative management. Previous literatures including operative indications are reviewed.