Background: Evidence-based medicine requires new skills of physicians, including literature searching.

Objective: To determine which literature retrieving method is most effective for GPs: the printed Index Medicus; Medline through Grateful Med; or Medline on CD-ROM.

Methods: The design was a randomized comparative study. In a continuing medical education course, three groups of health care professionals (87 GPs and 16 other health care professionals) used one of the literature retrieval methods to retrieve citations on four search topics related to general practice. For the analysis in pairs, we used the search results of the 75 participants who completed all four assignments. As outcome measures, we used precision, recall and an overall search quality score; we also had a post-course questionnaire on personal characteristics, experience with computers, handling medical literature and satisfaction with course instruction and search results.

Results: The recall and overall search quality scores in the Index Medicus groups (n = 32) were higher (P = <0.001) than those in the CD-ROM groups (n = 31). In addition, the search quality scores in the Grateful Med groups (n = 12) were higher (P < 0.003) than those in the CD-ROM groups. There were no differences in precision.

Conclusion: In the period 1994-1997, the printed Index Medicus was the most effective literature retrieval method for GPs. For inexperienced GPs, there is a need for training in electronic literature retrieval methods.