To determine the incidence of peripheral intravenous therapy-related phlebitis in an adult population, 305 peripheral IV catheter sites were observed from the time of admission of the patient (or initiation of the first peripheral IV catheter) to the time of the participant's discharge from the facility (or 48 hours after the removal of the final catheter). Parameters monitored included patient demographics, diagnosis, IV fluids and medications, type of peripheral catheter, dwell time, and dressing integrity. Results showed that of the 10 cases of phlebitis found in nine study subjects, all were associated with catheters indwelling less than 72 hours. In three cases, although the catheter site was clear at the time of catheter removal, postinfusion phlebitis developed within 24 hours. Catheter site locations, diagnoses, medications, and IV fluids in these cases were varied.