Medical workplace learning consists largely of individual activities, since workplace settings do not lend themselves readily to group learning. An electronic Learning Management with System Computer-Supported Collaborative Learning (CSCL) could enable learners at different workplace locations to discuss personal clinical experiences at a distance to enhance learning. To explore whether CSCL-enabled structured asynchronous discussions on an authentic task has additional value for learning in the medical workplace. Between January 2008 and June 2010, we conducted an exploratory evaluation study among senior medical students that were engaged in clinical electives. Students wrote a Critical Appraisal of a Topic paper about a clinical problem they had encountered and discussed it in discipline homogeneous subgroups on an asynchronous forum in a CSCL environment. A mixed method design was used to explore students' perceptions of the CSCL arrangement with respect to their preparation and participation, the design and knowledge gains. We analysed the messages recorded during the discussions to investigate which types of interactions occurred. Students perceived knowledge improvement of their papers. The discussions were mostly task-focused. The students considered an instruction session and a manual necessary to prepare for CSCL. A high amount of sent messages and a high activity in discussion seem to influence scores on perceptions: 'participation' and 'knowledge gain' positively. CSCL appears to offer a suitable environment for peers to provide formative feedback on a Critical Appraisal of a Topic paper during workplace learning. The CSCL environment enabled students to collaborate in asynchronous discussions, which positively influenced their learning.