Background: Medication monitoring in cancer patients receiving injectable chemotherapy drugs has shown prescribing errors and administrating errors. These caused several serious adverse drug reactions (ADR). Multidisciplinary team has been established to provide care for systemic problem solving. This study aimed to assess pharmacist role in management of therapy related problem and prevention of repeated serious therapy problems.Methods: Prospective descriptive study was performed. Patients receiving injectable chemotherapy drugs, in Surin Hospital, during October 1 2010 to September 30 2012 (Fiscal year 2011 and 2012) were included. Pharmaceutical care was provided to the patients. Descriptive statistics were analyzed.Results: There were 2,365 patients with 3,927visits. Cytotoxic drugs were prepare to 8,705 doses. Pharmaceutical care provided to cancer patients were 2,802 times, 290 drug information services, 2,802 nutrition consults and 69 reimbursement team consults. We found 1,348 drug related problems which the most problems were ADR (78.0%), medication error (9.5%), needed for additional drug therapy (3.1 %), improper dosage regimen (3.1%), improper drug selection (0.2 %), non compliance (4.7%), failed to receive medication (3.0%), drug interaction (0), duplication of medications (0) and other problems (1.3%). Side effects were the most frequent ADR (99.3%) and serious ADR were 20.4%. Drug related problems were solved 97.8% and all serious ADR could be prevented. There were 2,802 pharmacist interventions.Conclusion: Regarding multidisciplinary team approach, pharmacist has a role in solving medication problems and preventing serious ADR. In addition, pharmacists review the order to ensure the accepted reimbursment of therapy.