In Korea, female workforce has reached more than 40% of total working population, but the effects of work on spontaneous abortion are yet to be examined. This study as conducted to investigate the occupational effects on spontaneous abortion. Medical insurance claim data were used to examine the effects of the employment status and industry of employment on spontaneous abortion. The study population was composed of females, aged $15{sim}44$, who were the beneficiary of medical insurance in the month of June, 1993. The working females covered by medical insurance for industrial workers, had the highest age-adjusted Spontaneous Abortion rate (SAB rate=claim frequency of spontaneous abortion/claim frequency of complication of pregnancy, childbirth and the puerperium), 6.65% whereas female dependants of medical insurance for industrial workers had the lowest age-adjusted SAB rate, 4.54%. Among industrial workers, the workers in manufacturing industry had the highest age-adjusted Spontaneous Abortion ratio(SAB ratio=claim frequency of spontaneous abortion/claim frequency of completly normal delivery), 43.2/100 whereas those in financing and service industry had age-adjusted SAB ratio, 16.2/100 and 20.5/100, respectively. The results of the study suggest the adverse effect of manufacturing Industry on reproduction. Work environments such as chemical exposures, overwork, awkard posture, and job stress should be further studied for their effects on reproductive functions of female.