The effect of problem-based learning (PBL) on nursing students' approaches to learning has received scanty attention in nursing education. The purpose of the present study was to evaluate the effect of PBL on students' approaches to learning in clinical nursing education. Using a one-group before-after quasi-experimental design, the revised two-factor Study Process Questionnaire (R-SPQ-2F) was administered to compare students' approaches to learning before and after a period of clinical education in which PBL was implemented. Focus group interviews were used to elicit from students their PBL experience. Of the 237 students who participated in the study, 187 returned the R-SPQ-2F, representing a response rate of 78.9%. Twenty-eight of the students also participated in focus group interviews. The R-SPQ-2F scores indicated that for the deep approach to learning, the post-test mean score was noticeably higher than that at the pre-test (p=0.005). No significant difference was observed between the pre-test and post-test mean scores for the surface approach to learning (p>or=0.05). The four themes inductively derived from students' descriptions of their clinical education experience (motivated to learn; self-direction in learning; active, interactive and student-centred learning; and enjoyment in learning) also suggested that the students adopted a deep approach to learning during a period of clinical education in which PBL was implemented.