Pharmacological and toxicological evaluations of medicinal plants are essential for drug development. Cycas circinalis and Ionidium suffruticosum are the two herbs which had been used since ancient times for treating various ailments traditionally in Indian system of Medicine (Siddha Medicine), but the medicinal effects of both the herbs were yet to be proved scientifically. The present study was done to evaluate the sub-acute toxicity of both the medicinal herbs as a preliminary part in proving its medicinal effect on maintaining the fertility of male. OECD guidelines 407 were followed for the sub-acute toxicity study. A total of 42 male Wistar rats were randomly divided into seven groups of 6 animals in each group for 3 dosages up to 28 days and each group was administered 250 mg/kg, 500 mg/kg, 1000 mg/kg body weight of C.circinalis and I.suffruticosu methanolic extracts. The hematological and biochemical parameters were analyzed and compared between the control and experimental group, there was only slight variations were noted and was found to be within the standard laboratory values and statistical analysis of the parameters showed i nsignificance. The histopathological examination of various vital organs of both control and experimental groups were compared and no abnormal architecture, morphological disturbances, desquamation, disorganization, infiltration and no destruction of the tissues were noted. The sub-acute toxicity study proves that the ethanolic extract of C.circinalis and I.suffruticosum, when given orally at concentration up to 1000mg/kg body weight did not exhibit any toxicological effect and proved to be safe until 1000mg/kg. © 2015 Elsevier B.V., All rights reserved.