Hospital-based adverse drug reaction (ADR) monitoring and reporting programs aims to identify and quantify the risks associated with the use of drugs. The present study was undertaken to characterize the pattern of ADRs reported in a tertiary care teaching hospital (Kasturba Hospital, Manipal) in South India. The study was conducted based on the ADRs reported between March 2004 and February 2005 (12 months) to the ADR reporting unit of the hospital. Evaluation of the data was done for various parameters which included patient demographics, drug and reaction characteristics, and outcome of the reactions. Assessment was also done for causality, severity, preventability, and predisposing factors. A total of 408 ADRs which were reported during the 12 months period were evaluated. The overall incidence of ADR calculated from the patient population was 0.15%. At least one ADR was reported in 1.14% of the hospitalised patients and in 0.012% of the outpatients. No significant difference was seen in the overall incidence of ADRs observed in males and females. Incidence of ADRs among elderly adults and older adults (0.23%) were significantly higher than other age groups. Type A reactions (72.5%) accounted for majority of the reports and a greater share of the ADRs were described to be very common (43.4%) in the literature. Dermatological system (23.5%) was the most commonly affected organ system with skin rash (10.5%) as the most frequently reported reaction. Antineoplastic agents (21.8%) was the drug class most commonly involved, while phenytoin (7.8%) was the individual drug most frequently reported. The suspected drug was withdrawn for the management of the ADR in majority (56.6%) of the reports. In 74.8% of the reports the patient recovered from the reaction at the time of evaluation. Upon causality assessment, majority of the reports were rated as probable (53.7%). Mild and moderate reactions accounted for 50.5 and 43.9%, respectively. In 28.7% of the reports, the reaction was considered to be preventable. At least one predisposing factor was present in 79.9% of the reports and the most common predisposing factors associated were polypharmacy and multiple disease state. Evaluating the relationship between patient characteristics and reaction characteristics, type A reactions were more common among elderly adults (85.92%) and type B reactions more common in adults (35.01%) compared to other age groups. In conclusion, the pattern of ADRs reported in our hospital is comparable with the results of studies conducted in hospital set up elsewhere. Our evaluations revealed opportunities for interventions especially for the preventable ADRs to ensure safer drug use.