This study was to examine the effects of simulation used additionally in clinical practicum and evaluate its applicability in an undergraduate nursing curriculum. A longitudinal survey was used to measure the changes on the scores of clinical competency, clinical confidence, critical thinking and problem solving ability of students(N=77) who had experienced simulation in the clinical practicum curricula throughout their junior and senior years. Variables were measured 4 times, at the beginning and the end of each year, and data were analyzed using repeated measures of ANOVAs. Clinical competency score in senior year improved significantly(t=-13.75, p <.001) whereas no significant changes in junior year. Clinical confidence and critical thinking disposition over 2 years showed significant increases(F=177.86, p <.001; F=247.79, p <.001, respectively). Problem solving ability increased throughout the junior and senior years, however, it did not make a significant difference at any point of measures.