Background. The objective of this study is to evaluate whether a single palliative cancer care workshop, which included information about drug prescribing, had an effect oil the opioid-prescription patterns of general practitioners in daily practice. Method. The opioid-prescription figures of 68 general practitioners who had participated in the workshop were aggregated from the computer system of the Regional Sick Fund. The prescription figures of a year before and a year after the workshop were compared and a control group of non-participants was included. Results. This study showed a limited efficacy of a palliative cancer care workshop oil the morphine-prescription figures of the general practitioners in daily practice. This limited effect did not accord with the results of a pre- and post-workshop questionnaire evaluating the attitudes of the same practitioners. Conclusion. A single workshop can not effectuate substantial changes in prescription behaviors. Possibilities for more reinforcements are discussed