Abstract: The effects of ingestion of freshly prepared ethanolic extracts of four medicinal plants much used in Jordan were investigated on social aggression as well as on the histology of the testes and preputial glands of intact male mice. Intra-gastric application of Cinnamomum camphora extract significantly inhibited attack on subjects by aggressive residents. This treatment in these mice also reduced preputial activity and resulted in aspermatozoia. In contrast, the administration of Eruca sativa or Nigella sativa extracts dramatically increased the attack to which the mice were subjected as well as enhancing the maturation and differentiation of testicular spermatozoa and augmenting the activity of the preputials. The latter histological effects were most evident with E. sativa extracts.