Objective: Study on efficacy of aerial parts extract of Urtica dioica L. in treatment of type 2 diabetic patients. Study population: type 2 diabetic patients of the outpatient clinic in the Qom Kamkar and Shahid Beheshti hospitals. Inclusion criteria: type 2 diabetic patients, patients aged 40 to 60 years, patients with fasting serum glucose level above 200 mg/dl, patients with blood glycosylated hemoglobin level above 8 percent, patients who despite using a combination of oral synthetic antidiabetic drugs, their blood glucose level is not within the normal range and thus need insulin injection but refuse to inject insulin. Exclusion criteria:patients with cardiac, renal, hepatic diseases, concomitant infections, pregnant women, women planning pregnancy, breast-feeding women. The intervention: Nettle aerial parts extract is administered to a group of 30 patients at the dose of one 500 mg capsule every 8 hours in addition to the oral synthetic antidiabetic drugs for 3 months and placebo is administered to another group of 30 patients every 8 hours in addition to the oral synthetic antidiabetic drugs for 3 months. At the end of the study, the blood glucose, glycosylated hemoglobin, creatinin, liver enzymes including SGOT and SGPT levels in the drug group and the placebo group are determined and compared with each other.