Antifertility effect of ethanol extracts of whole plant of Asystasia travancorica Bedd. and Sonerlia tinnevelliensis were observed in male albino rats. The relative weight of the testis and epididymis were decreased. The epididymal sperm count, motility, and sperm abnormality were reduced significantly in plant extracts-treated rats. There was a decrease in serum protein: albumin and globulin and increase in urea, creatinine, and the activity of liver marker enzymes such as serum glutamate pyruvate transaminase, serum glutamate oxoloacetic transaminase, and alkaline phosphatase levels in plant extracts-treated rats. The results of the hormonal assay showed that increased levels of follicle stimulating 326hormone and estrogen but decreased in the serum level of luteinizing hormone and testosterone compared to control. The results of fertility examination showed that the adult treated male rats reduced the number of females’ impregnation. In addition, the number of implantations and the number of viable fetuses were also decreased. The results of the present study suggested that, ethanol extract of whole plant of Asystasia travancorica and Sonerila tinnevelliensis inhibited sperm concentration, motility, and testosterone level.