en Original Article Original Article <strong>Background: </strong>Physalis alkekengi (P. alkekengi)has been used as an abortive plant in Iranian traditional medicine for many years.<br> <strong>Objective:</strong> To investigate the effects of P.alkekengi on the fertility rate in female rats.<br> <strong>Material and Methods:</strong> In this experimental study, 40 female albino rats were divided randomly into two groups; group 1/for investigating the implantation sites and group 2/ for investigating the number and weight of neonates. In both groups, treated animals received plant extract at dose of 150 mg/kg on days 1-5 of pregnancy. In group 1, treated animals were euthanized at 7th days of pregnancy and number of implantation sites were counted. In group 2, treated animals maintained till delivery time and after delivery, the number and weight of neonates were investigated.<br> <strong>Results:</strong> Data showed that administration of P. alkekengi extract on days 1-5 of pregnancy significantly decreased the number of implantation sites, number and weight of neonates.<br> <strong>Conclusion: </strong>These results suggest that the extract produced anti- fertility effect probably by inhibiting implantation. Physalis Alkekengi, Rat, Implantation, Anti-fertility 13 16 http://ijrm.ir/browse.php?a_code=A-10-549-269&slc_lang=en&sid=1 Azadeh Montaserti Montaseri_azi@yahoo.com Yes Reproduction Research Center, Kermanshah University of Medical Sciences, Kermanshah, Iran Maryam Pourheydar No Reproduction Research Center, Kermanshah University of Medical Sciences, Kermanshah, Iran Mozafar Khazaei No Reproduction Research Center, Kermanshah University of Medical Sciences, Kermanshah, Iran Rostam Ghorbani No Reproduction Research Center, Kermanshah University of Medical Sciences, Kermanshah, Iran