Abortion is illegal in Iran and many women with unplanned pregnancies undergo clandestine, unsafe abortions. This study utilizes data from the 2009 Tehran Survey of Fertility, conducted in a sample of 2934 married women aged 15-49 in the city of Tehran, to estimate abortion rates and ratios and to explore reasons for abortions. The lifetime abortion rate is estimated to be one per six married women, and about 9 percent of pregnancies end in abortions. Annually, 11,500 abortions are estimated to be obtained by married women in Tehran. The mean age of women at abortion is 33.5 years. The probability of abortion is higher among women who are less religious, wealthier, employed, and among those who are childless or have two children. Findings suggest the existence of a male imposition in seeking an abortion. Reasons for abortions indicate that 84% of abortions in Tehran are most likely illegal, and birth spacing and limiting are the main reasons for seeking abortions. About two-thirds of aborted pregnancies resulted from failures in withdrawal, the pill, and condoms. Results of this research can help policymakers in reproductive health to identify subgroups in particular need of services and counseling to prevent unintended pregnancy.