OBJECTIVE: The transmuscular quadratus lumborum (TQL) block and the oblique subcostal transversus abdominis plane (OSTAP) block both contribute to multimodal analgesia after laparoscopic surgery. The objective of this study was to compare the analgesic effects of the TQL block versus OSTAP block after laparoscopic hysterectomy. DESIGN: Prospective single-centre randomised single-blind trial. SETTING: University-affiliated hospital. PARTICIPANTS: Patients aged between 18 and 65 years scheduled for laparoscopic hysterectomy. INTERVENTIONS: Patients were randomised into two groups (1:1 ratio) and received bilateral TQL block or bilateral OSTAP block with 0.375% ropivacaine 20 mL on each side before surgery. PRIMARY AND SECONDARY OUTCOME MEASURES: The primary outcome measure was the cumulative morphine dose in the first 24 hours. The secondary outcome measures were the morphine consumption at each time interval after surgery, the time from the end of surgery to the first need for morphine, the Numerical Rating Scale (NRS) scores for visceral and incisional pain intensity, and the incidence of adverse events. RESULTS: The cumulative morphine dose was significantly lower in the TQL group than in the OSTAP group (17.2 (12.5) vs 26.1 (13.3) mg, p=0.010). Compared with the OSTAP group, the morphine doses from 6 to 12, 12 to 18, and 18 to 24 hours were significantly lower, the time of first need for morphine was significantly longer and the NRS scores for visceral pain intensity were significantly lower in the TQL group. CONCLUSION: Compared with the OSTAP block, the TQL block reduced morphine consumption and provided better visceral pain relief with a longer duration of effect after laparoscopic hysterectomy. TRIAL REGISTRATION NUMBER: Chinese Clinical Trial Registry (ChiCTR1800017995); pre-results.