Introduction: To evaluate the adverse drug reactions (ADRs) due to cancer chemotherapy in a tertiary care hospital in South India. Materials and Methods: This was a retrospective descriptive study. The data was obtained from patients who developed, at least, one ADR due to cancer chemotherapy during the period June 2014 to May 2015. The causality of the ADRs were evaluated by WHO-UMC causality assessment system and Naranjo's ADR probability scale, the severity of ADRs were assessed by Hartwig and Siegel ADR severity assessment scale, and preventability of ADRs were determined by the Schumock and Thornton ADR preventability assessment scale. Results: One hundred fourteen ADRs due to cancer chemotherapy were reported in 73 patients. Hyponatremia (20.2%), neutropenia (11.4%), infections of the lung (11.4%), leucopenia (9.6%) were the commonly suspected ADRs. Cisplatin (62.3%), carboplatin (18.4%), cetuximab (3.5%), gefitinib (2.6%) were the commonly suspected medications. As per the WHO-UMC causality assessment system 66(57.8%) ADRs were possible and 48(42.1%) were probable. Naranjo's ADR probability scale showed that 74(64.9%) ADRs were possible and 40 (35.1%) were probable. There was a very good agreement between the two scales (kappa=0.853). All ADRs were classified as level 4 severity barring one. None of the ADRs reported were preventable. Conclusion: Since 80% of the ADRs were suspected to be due to platinum containing anticancer drugs this provides a focus for further research on devising methods for prevention or early detection of ADRs. Prompt detection of ADRs is important to decrease morbidity and mortality.Key words: Adverse Drug Reaction, Cancer Chemotherapy, Naranjo's ADR probability scale, Causality assessment, Pharmacovigilance, WHO-UMC causality assessment system. Correspondence RESULTSOne hundred fourteen ADRs due to cancer chemotherapy were reported in 73 patients during the study period. Among the ADRs reported, 63(55.3%) were in males and 51(44.7%) in females. The mean age of the patients was 55.98 ± 6.53 years in males and 52.96 ± 10.09 years in females. Oropharyngeal malignancy (24.6%) was the most common groups of cancers followed by malignancy affecting the digestive organs (16.7%), female genital organs (15.8%) and breast (7%). Among these, malignancy of cervix uteri (14.9%) and esophagus (14.9%) were the most common cancers. The gender-wise distribution of different malignancies is shown in Table 1. ADRs affecting blood (38.5%) were the most common suspected category of ADR, followed by metabolic abnormalities (29.8%) and infections (15%). Table 2 shows the various ADRs reported in the study population. Hyponatremia (12%), respiratory tract infection (9%) and neutropenia (7%) accounted for 44.4% of the ADRs in males. Hyponatremia (21.6%); neutropenia, diarrhea, anemia (11.8%); leucopenia, thrombocytopenia (9.8%) accounted for 76.6% of the ADRs in females. Seventy-four (64.9%) ADRs were considered to be recovering at the time of reporting, 253 impairing host protective mechanisms...