Acute hamstring muscle injury is the most frequent cause of acute posterior thigh pain, but referred pain to this area is also common. This chapter will focus only on acute hamstring injuries that are detectable on MRI (structural hamstring injuries). Hamstring injuries remain a challenge for clinicians, athletes, and coaches given the high incidence rate and often with persistent symptoms. The primary objective of all rehabilitation protocols is to return the athlete as soon as possible to the prior level of performance with a minimal risk of injury recurrence. The aim of this chapter is to describe the management of acute hamstring injuries including clinical examination, rehabilitation exercises, and return-to-sport criteria.