This study surveyed and analyzed all the cases ever filed omplains to the Consumers' Foundation because of medical disputes. Out of 203 questionnaires that were mailed out, 100 valid responses were received after two reminding postcards. Important findings are as follows: When dissatisfied with a medical service, the most frequently action taken by respondents was to complaint privately, followed by to report to the Consumer's Foundation. Among the respondents, those who were older, being female patients, being physically disabled or mentally retarded because of the medical malpratice, having taken strategic interactions, those whose significant others thought the medical staff were to be blamed, had stronger intentions to complain. In terms of respondents satisfaction toward the Consumers' Foundation, the overall difference （ gap ） between the respondents' expected and actual services received from the Consumer's Foundation was not statistically significant. However, further examination on the respondents' characteristics showed that those who thought the risk to complain was high, those who perceive the medical services were poor, the results were different from what the physician promised, the treatment resulted adversely, the malpractice resulted in disability or death, those who valued the effects were serious, those whose relatives thought the medical staff were to be blamed, those who were encouraged by their family or other medical practitioners to ask for compensation, and those who knew about the Foundation through their reference group, had worse perceptions about the Foundations's services. Suggestion to medical providers and the Consumers' Foundation were included.