Background and purposeData on incidence and on trends in treatment of hamstring injuries, including proximal hamstring tendon avulsions (PHA), is limited. We aimed to investigate the incidence, trends in operative treatment, age, and sex distribution of hamstring injuries in Sweden between 2001 and 2020.Patients and methodsWe obtained data recorded in the National Patient Register between 2001 and 2020 on patients between 18 and 90 years of age, with the ICD-10 code S76.3, to calculate the incidence of patients treated operatively for hamstring injuries in Sweden. Patients with the NOMESCO classification NFL49 were considered as having been treated operatively. Data on quadriceps and Achilles tendon injuries were obtained for comparison. To calculate incidences, adult population data for every year were obtained from the Statistics Sweden website.ResultsThe incidence of patients diagnosed with hamstring injuries increased from 2.2 to 7.3 per 100,000 person-years. There was a rising trend of surgical treatment per diagnosed case from 3.0% to 14.2%. Patients diagnosed in units with the highest experience of surgical treatment of hamstring injuries tended to be operated on more often (22.2%) than patients diagnosed in units with limited experience (5.1%), although the fraction of operated patients was increasing in both groups.ConclusionBetween 2001 and 2020 there was an increase in the proportion of operatively treated hamstring injuries.