Aim: The aim of this descriptive and cross-sectional study was to determine the knowledge and practices of nurses related to the prevention of peripheral intravenous therapy (PIT) complications, and to identify the influencing factors. Methods: The study adopted a cross-sectional and descriptive design and was conducted between April and August of 2018 with a total of 214 clinical nurses. The data collection tools employed were a 12-item sociodemographic questionnaire and a 16-item questionnaire on knowledge and practices related to the prevention of peripheral intravenous therapy complications. Results: The mean knowledge scores of the nurses were found to be 81.54 +/- 12.06 (min: 50, max: 100). No statistically significant difference was found to exist between the scores, and the variables of the nurses' gender, length of employment in the health profession, type of work, training received related to PIT complications, and self-competence level in PIT complications. Conclusion: The nurses were found to have high knowledge levels; however, their practices for preventing PIT complications differed. Standardized practice procedures and workplace training are needed in order to transform nurses' knowledge into practice with regard to the prevention of PIT complications.