This study was aimed to investigate the effects of Melatonin at )10mg/kg( on programmed cell death (apoptosis)by measurements Caspase -3 activity and antioxidant enzymes GSH, CAT, MDA, Peroxinitrate activity on rats exposed to anticancer drugs Gemcitabine. Sixty four adult male albino rats were used in this study ,weighing (250-350)gm with temperature 22±20C , The animals were feeding and drinking water ad libitum . the animals were divided into 5 main groups as following :Group A( Control group n=8 ) given a daily D.W. Group B:(melatonin group n=8)given a daily melatonin 10mg/kg/orally. Group C (Gemcitabine n=16)this group was divided into two group according to Gemcitabine dose (25 and 50 mg/kg).Group D (protective group n=16): this group was divided into two group according to Gemcitabine dose (25 and 50 mg/kg ) together with given a daily melatonin in dose (10mg /kg) orally. Group E (protective and treatment group n=16) : this group was divided into two group according to Gemcitabine dose (25 and 50 mg/kg ). This group was given a daily melatonin in dose (10mg /kg) orallyas a treatment. The results showed that melatonin reduced the activity of Caspase-3 enzyme (Apoptosis marker), MDA and peroxynitrate , that induced by chemotherapy drug ,While increased the activity of antioxidant enzyme GSH and CAT. Melatonin given protective effect on liver and kidney tissues from damaged that happened by Gemcitabine at two different dose (25,50 mg/kg ).