The present study was aimed to assess the incidence of phlebitis and identify the factors that cause phlebitis in children with a peripheral intravenous cannula.A prospective observational study was conducted between 15 July 2022 to 30 November 2022 in pediatrics wards of a tertiary care hospital. 225 children with PIVC were included in the study. PIVC was observed till phlebitis developed or maximum for seven consecutive days after enrollment. Phlebitis was defined by using the Jackson VIP scale. The incidence of phlebitis was 54.22% at 95% confidence interval. There was a significant association between phlebitis and the use of crystalloids, frequency of PIVC handling per day, use of cancer drugs, and use of a three-way, method of drug administration. The mean life span of PIVC was 69.86 ±32.88 hours, and the range was 19-180 hours.The incidence of phlebitis is much higher than the acceptable limit as per Infusion Therapy Standards of Practice which should be reduced. Crystalloids, the Method of drug administration, and cancer drugs are the risk factor for phlebitis. The study suggests that most likely phlebitis occurs after three days.