The appropriate use of antimicrobial agents is crucial for patient’s safety and public health. One way of optimizing antibiotic use is to switch earlier from intravenous to oral therapy. The main types of conversion are sequential therapy, switch therapy and step down therapy. The aim of the study is to evaluate the practice of conversion of intravenous (IV) to oral antibiotics and to assess the rationality of antibiotic therapy. A prospective observational study was done for a period six months at a tertiary care hospital, Palakkad. A standardized data entry form was prepared to record all patient details, investigations and therapy given. About 145 patients were observed and the study shows that cephalosporins (56.5%) were the mostly prescribed IV antibiotics. Step down type conversions were mostly observed type of conversion that is of 45.3% followed by switch type (35.9%) and sequential type (18.7%). Polypharmacy was the major cause for irrationality.