Iran experienced a dramatic decline in fertility from 1984 to 2001, which was most rapid in rural areas. Although many attribute the decline to the government's active participation in providing family planning services, most services were provided after the initial fertility decline that took place after 1984. We assess the extent to which timing of exposure to basic healthcare is related to fertility outcomes. We estimate the association between a woman's age of exposure to a health house (clinic) and number of children, using the 2001 Iranian Household Expenditure and Income Survey and the 2006 Iranian Census, and the location and dates of operation for each rural health house. We also look at the probability of a woman's giving birth one year after a clinic opened in her village. We use Poisson and logistic multivariate regressions and we control for individual, household, and village characteristics. Exposure to a health house in a woman's most fertile years (20–34) is associated with an 18 percent decrease in number of children ever born relative to those exposed after age 40. This negative association gets progressively stronger as length of exposure increases. Our findings suggest that early exposure to health services in rural areas contributed to Iran's fertility decline.