the objective of this prospective study is to verify the incidence of phlebitis among patients with peripheral intravenous catheters and to identify possible relations between this complication and catheter-related variables. seventy-six adult patients hospitalized in a brazilian university hospital were evaluated, using charts with patient-related variables, peripheral intravenous catheters, and pharmacological therapy. phlebitis was evaluated based on infusion nurses society proposed classification. inferential and descriptive statistics have been used. we observed 25.8% incidence of phlebitis, from which 40% presented pain occurrences, with erythema and edema. among patients with phlebitis, 60% developed a complication episode, and the average period of permanence of peripheral intravenous catheters with phlebitis was 3.10 days. we observed phlebitis associations to adverse occurrences during the removal of peripheral intravenous catheters (p<0.001). educational actions and professional training for nursing personnel are necessary for dealing with intravenous therapy, mainly on what is related to early detection of phlebitis.