To evaluate the impact of Mexico's conditional cash transfer programme on the quality of health care received by poor women. Quality is measured by maternal reports of prenatal care procedures received that correspond with clinical guidelines. The data describe retrospective reports of care received from 892 women in poor rural communities in seven Mexican states. The women were participating in an effectiveness study and randomly assigned to incorporation into the programme in 1998 or 1999. Eligible women accepted cash transfers conditional on obtaining health care and nutritional supplements, and participated in health education sessions. Oportunidades beneficiaries received 12.2% more prenatal procedures compared with non-beneficiaries (adjusted mean 78.9, 95% Confidence Interval (CI): 77.5–80.3; P < 0.001). The Oportunidades conditional cash transfer programme is associated with better quality of prenatal care for low-income, rural women in Mexico. This result is probably a manifestation of the programme's empowerment goal, by encouraging beneficiaries to be informed and active health consumers.