Aims. Despite the increase in the surgical repair of proximal hamstring tears, there exists a lack of consensus in the optimal timing for surgery. There is also disagreement on how partial tears managed surgically compare with complete tears repaired surgically. This study aims to compare the mid-term functional outcomes in, and operating time required for, complete and partial proximal hamstring avulsions, that are repaired both acutely and chronically. Methods. This is a prospective series of 156 proximal hamstring surgical repairs, with a mean age of 48.9 years (21.5 to 78). Functional outcomes were assessed preinjury, preoperatively, and postoperatively (six months and minimum three years) using the Sydney Hamstring Origin Rupture Evaluation (SHORE) score. Operating time was recorded for every patient. Results. Overall, significant improvements in SHORE scores were seen at both six months and mid-term follow-up. Preoperatively, acute patients (median score 27.1 (interquartile range (IQR) 22.9)) reported significantly poorer SHORE scores than chronic patients (median score 42.9 (IQR 22.1); p < 0.001). However, this difference was not maintained postoperatively. For partial tears, acutely repaired patients reported significantly lower preoperative SHORE scores compared to chronically reapired partial tears (median score 24.3 (IQR 15.7) vs median score 40.0 (IQR 25.0); p < 0.001) but also significantly higher SHORE scores at six-month follow-up compared to chronically repaired partial tears (median score 92.9 (IQR 10.7) vs. median score 82.9 (IQR 14.3); p < 0.001). For complete tears, there was only a difference in preoperative SHORE scores between acute and chronic groups. Overall, acute repairs had a significantly shorter operating time (mean 64.67 minutes (standard deviation (SD) 12.99)) compared to chronic repairs (mean 74.71 minutes (SD = 12.0); t = 5.12, p < 0.001). Conclusion. Surgical repair of proximal hamstring avulsions successfully improves patient reported functional outcomes in the majority of patients, irrespective of the timing of their surgery or injury classification. However, reducing the time from injury to surgery is associated with greater improvement in patient outcomes and an increased likelihood of returning to preinjury functional status. Acute repair appears to be a technically less complex procedure, as indicated by reduced operating times, postoperative neurological symptoms and number of patients requiring bracing. Acute repair is therefore a preference among many surgeons. Cite this article: Bone Joint J 2020;102-B(10):1419–1427