The purpose of this study was to examine students' conception of their learning in a problem-based learning medical curriculum. A multiple case study design was used with two units of analyses: two PBL lab groups; and 15 individual students within each lab group. Data collected included weekly journals by students, video-tapes of PBL sessions, focus group interviews with students, two open-ended questionnaires completed by students, and interviews with the PBL tutors. Three thematic categories of students' conceptions of their learning emerged: (1) awareness of PBL goals and expectations; (2) efficiency and expertise; and (3) the role of the tutor.