AbstractToxicity studies were done on six plants used in the traditional Arab system of medicine, namely:Aloe vera, Ammi majus, Areca catachu, Citrullus colocynthis, Cuminum cyminumandZizyphus spina‐christi.During acute toxicity tests, observations were made for 24 h while the animals were treated for 3 months in chronic treatment. External morphological changes, visceral toxicity, haematological changes, and spermatogenic dysfunction, besides effects on average body weight and vital organ weight, were recorded. In the acute toxicity test,C. colocynthisshowed a dose dependent toxic effect. On chronic treatment, per cent lethality was found to be significant inA. catachu, A. veraandC. colocynthistreated groups where haematological changes were also observed. The spermatogenic dysfunction was significant in A. vera andC. colocynthistreated animals.C. cyminumandZ. spina‐christion the other hand, reduced sperm abnormalit