Maternal factors such as salpingitis and peritubal adhesion are known to be associated with ectopic pregnancy; however, a few studies have considered the chromosomal complements of ectopic conceptuses. We studied 16 ectopic conceptuses obtained by surgical resection. The karyotyping of chorionic villi was performed using direct and culture technique. Among 16 studied cases, 14 cases showed normal karyotype (nine with 46, XY; five with 46, XX). One case showed trisomy 16(47, XY, + 16) and another showed variation from normal chromosomal complement (46, XY, 14s+), resulting in 6.3% incidence of the structural abnormalities of the chromosome. On the basis of our study, we determined the possibility of chorionic villi karyotyping in ectopic pregnancy. This ectopic conceptuses are no more likely to show chromosomal abnormalities than in utero conceptuses of comparable gestational age. Therefore, maternal factors such as salpingitis and peritubal adhesion are the most likely explanations for ectopic pregnancy.