OBJECTIVE: To evaluate the efficacy and safety of up to 24 weeks of triptorelin treatment after conservative surgery for deep infiltrating endometriosis (DIE). DESIGN: Multicentre, prospective, non-interventional. SETTING: 18 tertiary hospitals in China. POPULATION: Premenopausal women aged ≥ 18 years treated with triptorelin 3.75 mg once every 28 days for up to 24 weeks after conservative surgery for DIE METHODS: Endometriosis symptoms were assessed, using a visual analogue scale (0–10 cm) or numerical range (0–10), at baseline (pre-surgery) and routine visits 3, 6, 9, 12, 18 and 24 months after surgery. MAIN OUTCOME MEASURES: Change in symptom intensity over time. RESULTS: A total of 384 women were analysed (mean [SD] age, 33.4 [6.2] years). Scores for all symptoms assessed (pelvic pain, dysmenorrhoea, ovulation pain, dyspareunia, menorrhagia, metrorrhagia and gastrointestinal and urinary symptoms) decreased from baseline over 24 months. Cumulative improvement rates in pelvic pain, dysmenorrhoea, ovulation pain and dyspareunia were 74.4%, 83.6%, 55.1% and 66.9%, respectively. The 24-month cumulative recurrence rate (≥ 1 symptom) was 22.2%. The risk of symptom recurrence was higher in patients with ≥ 2 versus 1 lesion (odds ratio [OR] 2.539; 95% CI: 1.458–4.423; p = 0.001) and patients with moderate (OR 5.733; 95% CI: 1.623–20.248; p = 0.007) or severe (OR 8.259; 95% CI: 2.449–27.851; p = 0.001) pain versus none/mild pain. Triptorelin was well tolerated. CONCLUSIONS: Triptorelin after conservative surgery for DIE improved symptoms over 24 months of follow up. FUNDING: Sponsored by Ipsen