CONTEXT: Many Japanese cases of adverse events after acupuncture are not listed in medical databases such as Medline. Therefore, they are not easily accessible to researchers outside Japan. OBJECTIVE: To complement existing reviews of adverse events after acupuncture in the West and to provide more detailed discussion and analysis. DATA SOURCES: Literature search using 'Igaku Chuo Zasshi (Japana Centra Revuo Medicina) CD-ROM version' covering the period of 1987-1999. STUDY SELECTION: Case reports of adverse events, which were suspected to be due to acupuncture treatment, were included. Experimental studies, surveys, and news articles were excluded. DATA EXTRACTION: Two independent reviewers extracted data from located articles in a pre-defined structured way, and assessed likelihood of causality in each individual case. DATA SYNTHESIS: 89 articles which reported 124 cases were located. The most frequent adverse events were: pneumothorax (25 cases), spinal cord injury (18 cases), acute hepatitis B (11 cases), and localized argyria (10 cases). There were two fatalities from infections. Forty-eight events were caused by needle breakage including 26 cases of intentionally embedded needle and 16 cases of accidental breakage. There were also 10 cases of injury from self-treatment. CONCLUSION: Although it has already been demonstrated that severe adverse events seem to be uncommon in standard practice, many serious cases of negligence have been found in the present review, suggesting that training system for acupuncturists (including medical doctors) should be improved and that unsupervised self-treatment should be discouraged.