Background: Adverse drug reactions (ADRs) associated with the use of anticancer drugs are a worldwide problem and cannot be overlooked. They range from nausea, vomiting or any other mild reaction to severe myelosuppression. The study was planned to evaluate the pattern of adverse drug events to anti-cancer agents in a tertiary care hospital. Methods: This observational prospective study was carried out in a tertiary care hospital from 1st January 2011 to 31st December 2011. A total of 213 patients who fulfilled the inclusion criteria were enrolled in the study. Out of them, 8 patients were withdrawn from the study as they subsequently underwent radiotherapy. The adverse events observed during the treatment were noted and analyzed by using applicable statistics. Results: Out of 205 patients, 98 were males and 107 were females. Breast cancer was the commonest type of cancer evident. A total 523 anti-cancer drugs were prescribed for the patients with alkylating agents being the most common. 635 adverse events (ADRs) were observed in patients with vomiting and nausea as the most common adverse drug reactions (ADREs). Majority of the ADRs (89%) had a latent onset (occurring 2 or more days after exposure to the drug). Few events were serious in nature (9%); fatal events were uncommon (0.31%). WHO causality was 'possible' for 94% of the events. ADRs were more frequently observed in females in the age group of 46-60 years; mood swings were significantly higher in women, while vomiting was found to be significantly common in men. Conclusions: The study showed that chemotherapy has a high potential to cause ADRs. Thus, there is a need for vigilant ADR monitoring to prevent morbidity and mortality due to ADRs.