Carrot (Daucus carota) is from apiacea family. This plant has many therapeutic properties including strengthening hematopoiesis processes. In this study, the effects of hydroalcoholic extract of carrot were studied on blood parameters in mice (Balb/C race). Fifty mature mice were divided in five groups randomly. Control group didn't received any extract, placebo group received 0.5 cc of normal saline every other day and four treatment groups received 50, 100 and 200 mg/kg/2 days as injections in peritoneum. At the end of period, blood samples were taken from heart. Obtained data were analyzed using SPSS program at 5% probability level. Evaluating blood parameters showed significant increase in 100 and 200 mg/kg groups in proportion to control group whereas red blood cells of these groups were decreased significantly in proportion to control group. Hemoglobin and hematocrit amounts were not changed in treatment groups but red blood cell indices (MCH, MCV) did not show significant differences. Results showed that carrot extract in 100 and 200 mg/kg doses could strengthen immune system by increase in white blood cells but reduction in red blood cells had negative effects on hematopoiesis