We compared expenditure trends for reproductive, maternal, neonatal and child health (RMNCH) with trends in RMNCH service coverage in Peru. We used National Health Accounts data to report on total health expenditure by source; the Countdown database for trends in external funding to RMNCH, and Ministry of Finance data for trends in domestic funding to RMNCH. We undertook over 170 interviews and group discussions to explore factors explaining expenditure trends. We describe trends in total health expenditure and RMNCH expenditure in constant 2012 US$ between 1995 and 2012. We estimated expenditure to coverage ratios. There was a substantial increase in domestic health expenditure over the period. However, domestic health expenditure as share of total government spending and GDP remained stable. Out-of-pocket health spending (OOPS) as a share of total health expenditure remained above 35%, and increased in real terms. Expenditure on reproductive health per woman of reproductive age varied from US$ 1.0 in 2002 to US$ 6.3 in 2012. Expenditure on maternal and neonatal health per pregnant woman increased from US$ 34 in 2000 to US$ 512 in 2012, and per capita expenditure on under-five children increased from US$ 5.6 in 2000 to US$ 148.6 in 2012. Increased expenditure on RMNCH reflects a greater political support for RMNCH, along with greater emphasis on social assistance, family planning, and health reforms targeting poor areas, and a recent emphasis on antipoverty and crosscutting equitable policies and programmes focused on nutrition and maternal and neonatal mortality. Increasing domestic RMNCH expenditure likely enabled Peru to achieve substantial health gains. Peru can provide useful lessons to other countries struggling to achieve sustained gains in RMNCH by relying on their own health financing.