The influences of acid-base imbalance on the hematological aspects of peripheral blood, bone marrow and spleen were studied in albino rats under the controlled environments including room temperature, diet, fluid supply etc. Acidosis and alkalosis were induced by intragastric ingestion of ammonium chloride and sodium bicarbonate, and was confirmed by blood gas analysis including pH and base excess. The results are summerized as follows : 1) The peripheral blood of the acidosis group showed an increasing tendency in RBC, Hb, Hct and reticulocyte count comparing to that of control & alkalosis groups. The WBC total counts were also increased in acidosis group with relative neutrophilia and lymphopenia while the alkalosis group showed marked relative neutropenia and lymphocytosis comparing that of acidosis group. 2) In the bone marrow, the acidosis group showed a decreased erythroid series with increased myeloid series and eosinophilia comparing to the control group. The alkalosis group showed a marked decrease in erythroid series and a marked increase in lymphoid cells comparing to those of control and acidosis groups. 3) In the spleen, the acidosis group showed a marked increase in nucleated red blood cells.