Venetoclax plus obinutuzumab has been established as a fixed-duration treatment regimen for patients with chronic lymphocytic leukaemia . We compared the long-term efficacy after treatment cessation of the combination of venetoclax plus obinutuzumab with chlorambucil plus obinutuzumab in patients with previously untreated chronic lymphocytic leukaemia . CLL14 is a multicentre, randomised, open-label, phase 3 trial done at 196 sites in 21 countries. Eligible patients were aged 18 years or older, had untreated chronic lymphocytic leukaemia, and coexisting conditions with a cumulative illness rating scale greater than 6, a creatinine clearance of 30–69 mL/min, or both. Patients were randomly assigned (1:1) via a web and voicemail system with allocation concealment and based on a computer-generated randomisation schedule with a block size of six and stratified by Binet stage and geographical region. Patients received either venetoclax plus obinutuzumab (oral venetoclax initiated on day 22 of cycle 1 [28-day cycles], with a 5-week dose ramp-up [20 mg, 50 mg, 100 mg, and 200 mg, then 400 mg daily for 1 week], thereafter continuing at 400 mg daily until completion of cycle 12; combined with intravenous obinutuzumab for six cycles starting with 100 mg on day 1 and 900 mg on day 2 [or 1000 mg on day 1], 1000 mg on days 8 and day 15 of cycle 1, and subsequently 1000 mg on day 1 of cycles 2 through 6) or chlorambucil plus obinutuzumab (oral chlorambucil at 0·5 mg/kg bodyweight on days 1 and 15 of each cycle for 12 cycles combined with the same obinutuzumab regimen). The primary endpoint was investigator-assessed progression-free survival in the intention-to-treat population. Safety was assessed in all patients who received at least one dose of study treatment. Patient enrolment is complete, and the study is registered with ClinicalTrails.gov , NCT02242942 . Between Aug 7, 2015, and Aug 4, 2016, 432 patients were enrolled and randomly assigned to receive either venetoclax plus obinutuzumab (n=216) or chlorambucil plus obinut...