Partial molar pregnancy is an uncommon thing in which there is usually a triploid atypical fetus accompanying with a large placenta with cystic changes. The incidence of a normal diploid fetus and a partial molar placenta is really uncommon. Here we report a case of partial molar pregnancy in which a normal looking fetus with diploid karyotype coexist. A focal placental abnormal region was noticed at 13 weeks of pregnancy as enlargement associated with cystic changes. Fetus showed no clear deformity. Concerning these findings, the patient continued her pregnancy under close observation and advanced sonographic evaluations were made to rule out other differentials. There were no obstetric complications until the 28th gestational week when vaginal bleeding occurred. The patient underwent caesarian section and the products were sent for pathologic assessment which confirmed the partial molar changes.