The aim of this study was to determine the changes of body weight, organ weight, hematological values and biochemical parameters by testosterone (Testos) on the orchidectomized (Orch) rats. The animals were divided into 4 groups. Intact group (n=10) received no treatment and operation. Sham group (n=10) received only sham operation and no treatment. Orch group received operation and no treatment. Orch+Testos received operation and testosterone. The body weights of each group increased, but that of Orch+Testos group was significantly lower in Orch+Testos group than in all the other groups. There were significant differences (P<0.05, P<0.001) of body weights between Orch+Testos group and all the other groups. Also, organ weights such as heart, liver, spleen and kidney were measured. The heart weights were significantly lower (P<0.001) in the Orch+Testos group than in all the other groups. The liver weights in the Orch+Testos group were significantly differences in comparison with those in the Sham (P<0.001) and Orch group (P<0.05). On the other hand, there were no significantly differences in the organ weights of spleen and kidney between the Orch+Testos group and the any other groups. The hematological values of white blood cell (WBC), red blood cell (RBC), mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH) and mean corpuscular hemoglobin concentration (MCHC) were no significant differences in any other groups. The concentrations of serum total protein and albumin increased significantly (P<0.05) in the Orch+Testos group as compared to that in the Orch group. However, there were no significant differences in Ca, IP and Mg in any other groups. We conclude that testosterone was significantly decreased the body weight in the orchidectomized rats. Our findings suggest that testosterone may influence the process of lipid packaging and absorption in the orchidectomized rats.