Objective and design: The effect of blood sampling site on the hemogram and neutrophil adhesion molecules was examined in BALB/c mice.¶Materials and methods: Blood samples were drawn from the tail, eye, and heart during anesthesia with ketamine and xylazine. Cell numbers were quantified with an automated counter and flow cytometry was used to quantify CD11b and CD18.¶Results: Total white blood cell (WBC) counts were highest from tail, lower from eye, and significantly lower from heart blood. In general, differences between tail and heart counts reflected changes in all cell types. RBCs, platelets and hematocrits were significantly increased in tail compared to heart blood. Although CD18 levels were not different, CD11b was significantly higher on neutrophils from tail compared to heart blood.¶Conclusions: In anesthetized BALB/c mice, sampling site readily influences blood counts and neutrophil CD11b. The findings underscore the need to standardize sampling site when measuring these parameters.