We investigated the antiemetic effect, safety and usefulness of granisetron tablet on nausea/vomiting induced by cytosine arabinoside (Ara-C) in the chemotherapy for tumors in the hematopoietic organs. Out of 52 cases with malignant tumors in the hematopoietic organs including acute leukemia, 30 in granisetron group had no antiemetic treatment, were evaluated for the clinical efficacy of granisetron and 22 in control group. Their chemotherapies were combination therapy with Ara-C and daunorubicin (DNR), Ara-C and mitoxantrone (MIT), or Ara-C and etoposide (VP-16). In the trial, the dosage of granisetron tablet was 2 mg once a day, and the drug was given before each chemotherapy for 6 consecutive days. In clinical efficacy the effective rate of granisetron (the percentage of cases in which the trial drug was assessed as "Remarkably effective" or "Effective") was more than 80% on each day of administration. There was no adverse event. As the abnormal laboratory test value, only 1 case tested positive in urine protein, whose causal relation to the trial drug was judged as "Unassessable". Granisetron was judged as "Safe" in 31 out of 32 cases (96.9%). In terms of usefulness, the drug was rated "Extremely useful" or "Useful" in 26 out of 30 cases (86.7%). The above results have shown that granisetron tablet, when administered orally once daily at a dose of 2 mg, has an excellent antiemetic effect, and is a safe and useful drug.