This study was designed to investigate the effect of an extract of Zingiber officinale Roscoe (Zingiberaceae) (ginger) on some hematologic values in alloxan-induced diabetic rats. Eighteen Sprague-Dawley rats were divided into three experimental groups: control, diabetic, and Z. officinale-treated diabetic. At the end of the experimental period (3 weeks), animals in all three groups were fasted for 12 h and blood samples were taken for the determination of glucose levels, red blood cell (RBC) count, white blood cell (WBC) count, packed cell volume (PCV), hemoglobin (Hb) concentration, and platelet count. It was found that Z. officinale treatment increased the lowered levels of RBC and WBC counts and PCV in diabetic rats (p < 0.05). However, the RBC count and PCV of the Z. officinale-treated diabetic group were still lower than control. Z. officinale treatment also decreased the elevated level of platelets and glucose concentration of diabetic rats (p < 0.05). It is therefore concluded that oral Z. officinale treatment might decrease the diabetic-induced disturbances of some hematologic parameters in alloxan-induced diabetic rats.