Background: the easiest method of reducing calories is to replace the high caloric food products with sweetened ones. Aim of the work: this study aimed to determine the effects of acesulfame-k or aspartame on some physiological parameters in male albino rats. Materials and methods: we used thirty male albino rats of local strain weighing from 100 to120 gm. The period of the experiment was 30 days. The animals were divided into three groups; Group 1: control, Group 2: rats received acesulfame-k (15 mg/kg/day) and group 3: rats received aspartame (50 mg/kg/day). Results: there was an increase in serum glucose and insulin level in rats that received aspartame. In addition, there was increase in ASAT and ALAT activities, serum creatinine, serum urea and lipid profile except HDL-C in both treated groups as compared to the control group. Meanwhile, there was a drop in serum testosterone level and serum T3&T4 levels in aspartame group as well as in total protein, albumin and albumin/globulin ratio in both treated groups as compared to control group. Conclusion: aspartame has more dangerous effects than acesulfame-k.