Due to the compounds such as thymol, para-fat, Lfapnyn, D Pntn, Gamatrpnyn, Btapnyn, limonene, myrcene and carvacrol, Ajowan is widely used in the treatment of various diseases. This study aims at evaluating the effect of aqueous extract of Carum copticum on renal indices in male wistar rats. In this study 72 rats were divided into 6 groups, including control, sham and experimental groups (1 to 4). The control group didn’t receive any treatment while the sham received 0.2 ml distilled water daily and 1 to 4 experimental groups received 200, 400, 600 and 800 mg/ kg/day of aqueous extract of C. copticum intraperitoneally, respectively. After lapse of 16 and 32 days, serum samples were collected. Renal indices were measured by Autoanalayzer (with Pars Azmoon kits) and sodium and potassium were measured by flame photometer. Data was analyzed by ANOVA statistical tests and Tukey test (p <0.05). Regardless of the dosage of the extract, it increased the renal function in short-term and long-term. Compared to the control group, while serum concentrations of sodium in exp. groups 1 and 3 (200 and 400 mg/ kg/day) was decreased in the short term, it was increased in the all experimental groups in long term. Administration of extract in both short and long terms increased serum concentrations of potassium in all experimental groups compared to the control group. This study suggests that increased consumption of aqueous extract of C. copticum increases renal function, although its effects are somewhat different in the short term and the long term.