The provision of breast pumps is a potential strategy to increase breastfeeding duration. This trial compared the effectiveness and acceptability of two breast pumps in mothers exclusively breastfeeding (EBF) their healthy term infant. It also tested whether provision of pumps versus vouchers of equivalent value influenced breastfeeding or attainment of mothers' goals at 3 and 6 months. Mothers were randomised at 3- to 4-week post-partum (Beijing [n = 30], Moscow [n = 34], London [n = 45], New York [n = 3]) to groups A (Philips single-electric pump, Natural bottle), B (Medela Swing single-electric pump, Calma bottle), or C (Control; vouchers). At 6 weeks, group A and B mothers expressed for 10 min/breast; milk weight and opinions of pump/bottle were recorded. Feeding practices were assessed using questionnaires at 3 and 6 months. Milk weight/flow pattern did not differ between groups. Pump A scored significantly better for ease-of-use, cushion-feel, need-to-lean-forward, pleasant, comfort. At 3 and 6 months, %EBF or meeting their goal was not significantly different; (3 months: 86%, 85%, 84%; 6 months: 20%, 15%, 26%; meeting goal 24%, 17%, 27% for A, B, and C). Expressed breast milk (EBM) provision was higher in groups A and B (3 months: 76%, 76%, 24% (p < 0.001); 6 months: 83%, 87%, 32% (p < 0.001); and negatively predicted EBF at 6 months (OR no EBM 5.07, 95% CI [1.56, 16.5]). The pumps were equally effective for milk expression at 6 weeks. Pump provision did not significantly influence breastfeeding practices or attainment of goals but resulted in higher EBM provision, which was associated with lower EBF but not other breastfeeding categories at 6 months.