Objective To compare rates of detectability of circulating Rh(D)‐immunoglobulin (anti‐D) at delivery with single and two‐dose antenatal anti‐D prophylaxis (RAADP) regimens; to compare compliance with the two regimens. Design Open label, randomised controlled trial between May 2013 and November 2015. Setting, participants 277 women who attended a tertiary obstetric referral hospital in Perth for antenatal care and were at least 18 years of age, less than 30 weeks pregnant and yet to receive RAADP, Rh(D)‐negative (negative antibody screen), and who intended to deliver their baby at the hospital. Exclusion criteria were prior anti‐D sensitisation, any contraindication of anti‐D administration, and a history of isolated IgA deficiency. Interventions One 1500 IU anti‐D dose at 28 weeks of pregnancy (single dose regimen); two doses of 625 IU each at 28 and 34 weeks of pregnancy (two‐dose regimen). Main outcome measures The primary outcome was the proportion of women with detectable anti‐D levels at delivery; the secondary outcome was compliance with the allocated RAADP regimen. Results Circulating anti‐D was detectable at delivery in a greater proportion of women in the two‐dose group (111 of 129, 86%) than in the single dose group (70 of 125, 56%; P < 0.001). Compliance was not significantly different between the single dose (86 of 138, 61%) and two‐dose groups (70 of 139, 50%; P = 0.06). Conclusions The two‐dose RAADP schedule currently recommended in Australia provides better protection against Rh(D) sensitisation than a one‐dose regimen. Trial registration Australian and New Zealand Clinical Trials Registry (ACTRN12613000661774).