BACKGROUND: Recent reports have suggested a significant change in the causes of blindness in children in low-income countries cataract becoming the leading cause. We aimed to investigate the presentations and surgical outcomes in children with cataract operated at different ages in Tanzania. METHODS: We conducted a prospective study of 228 children aged ≤192 months at three tertiary centres, 177 with bilateral cataracts and prospectively followed them for 1-year postsurgery. We collected demographic, surgical, preoperative and postoperative clinical characteristics using the standard childhood cataract surgical assessment questionnaire. Families were encouraged to return for follow-up by phone with travel reimbursement where necessary. RESULTS: Preoperatively, 76% bilateral children were blind in the better eye. 86% of children were followed up at 1 year and 54% bilateral children achieved visual acuity of 0.48 logMAR or better in the better eye and 5% were blind. 33% of unilateral children achieved visual acuity of 0.48 logMAR or better and 17% were blind. Preoperative blindness (adjusted OR (AOR) 14.65; 95% CI 2.21 to 97.20), preoperative nystagmus/strabismus (AOR 9.22; 95% CI 2.66 to 31.97) and aphakia (AOR, 5.32; 95% CI 1.05 to 26.97) predicted poor visual outcome in bilateral cases. 9% of 342 refracted eyes had initial postoperative cylinder of 1.5 D or more, as did a similar proportion (11%) of 315 eyes refracted 1 year after surgery. Acute fibrinous uveitis occurred in 41 (12%) eyes. CONCLUSION: Three-quarters of children were blind preoperatively whereas over half had good vision 1-year postoperatively. Preoperative blindness, nystagmus/strabismus and aphakia predicted poor visual outcome, suggesting that cataract density determines density of amblyopia.