Objectives: To investigate the extent to which family physicians in Lithuania inform their patients about possible side-effects when a common treatment is proposed. To examine the relation between physicians’ estimation of the severity and frequency of these side-effects and their willingness to inform patients. To identify the reasons for informing or not informing the patients.Methods: A questionnaire, presenting three hypothetical cases involving decisions about ordinary medical treatments and a series of general questions about information about side-effects, was distributed to 500 (...) Lithuanian GPs. The response rate was 42%.Results: The respondents differed considerably with regard to their willingness to inform patients about side-effects, but they informed their patients significantly more if the side effect was considered to be common and serious, than in cases when it was considered to be rare and trivial. The majority of the respondents informed their patients primarily to enable them to react appropriately to the side-effects in question. The major reason for not informing was that the side-effects were considered too rare to be relevant to the patient’s decision-making.Conclusion: Information, given to patients about side-effects by Lithuanian GPs, is not in accordance with the principle of respect for patients’ autonomy and requirements of Lithuanian legislation. (shrink)