Background: This two-stage randomised controlled trial, comparing total laparoscopic hysterectomy (TLH) with total abdominal hysterectomy (TAH) for stage I endometrial cancer (LACE), began in 2005. The primary objective of stage 1 was to assess whether TLH results in equivalent or improved quality of life (QoL) up to 6 months after surgery compared with TAH. The primary objective of stage 2 was to test the hypothesis that disease-free survival at 4·5 years is equivalent for TLH and TAH. Here, we present the results of stage 1. Methods: Between Oct 7, 2005, and April 16, 2008, 361 participants were enrolled in the QoL substudy at 19 centres across Australia, New Zealand, and Hong Kong; 332 completed the QoL analysis. Randomisation was done centrally and independently from other study procedures via a computer-generated, web-based system (providing concealment of the next assigned treatment), using stratified permuted blocks of three and six patients. Patients with histologically confirmed stage I endometrioid adenocarcinoma and Eastern Cooperative Oncology Group performance status less than 2 were randomly assigned to TLH (n=190) or TAH (n=142), stratified by histological grade and study centre. Patients and study personnel were not masked to treatment assignment. QoL was measured at baseline, 1 and 4 weeks (early), and 3 and 6 months (late) after surgery, using the Functional Assessment of Cancer Therapy-General (FACT-G) questionnaire. The primary endpoint was the difference between groups in QoL change from baseline at early and late timepoints (a 5% difference was considered clinically significant). Analysis was done according to the intention-to-treat principle. Patients for both stages of the trial have now been recruited and are being followed up for disease-specific outcomes. The LACE trial is registered with ClinicalTrials.gov, number NCT00096408. Findings: Eight of 332 patients (2·4%) had treatment conversion—seven from TLH to TAH and one from TAH to TLH (patient preference). In the early phase of recovery, patients who had TLH reported significantly greater improvement in QoL from baseline compared with those who had TAH, in all subscales apart from emotional and social wellbeing. Improvements in QoL up to 6 months after surgery continued to favour TLH, except in the emotional and social wellbeing measures of FACT and the visual analogue scale of the EuroQoL five dimensions (EuroQoL-VAS). Operating time was significantly longer in the TLH group (138 min [SD 43]) than in the TAH group (109 min ; p=0·001). Although the proportion of intraoperative adverse events was similar between groups (TAH eight of 142 [5·6%] vs TLH 14 of 190 [7·4%]; p=0·53); postoperatively, twice as many patients in the TAH group experienced adverse events of grade 3 or higher (33 of 142 [23·2%] vs 22 of 190 [11·6%] in the TLH group; p=0·004). Postoperative serious adverse events occurred more in the TAH group (27 of 142 [19·0%]) than in the TLH group (16 of 190 [7·9%]; p=0·002). Interpretation: QoL improvements from baseline during early and later phases of recovery, and the adverse event profile, favour TLH compared with TAH for treatment of stage I endometrial cancer.