The authors developed and designed pictographic medication instructions based on the storyboard pictogram concept and then evaluated the pictograms during an itinerant medical mission in Gabon. Patients' comprehension of both the individual pictograms and the storyboard template were evaluated at the time of dispensing or at short-term follow-up. Patients were asked questions to assess their comprehension of the indication, dose, route of administration, frequency and auxiliary instructions. Demographic data, including age, sex and mother tongue, were also collected. During the follow-up interview, the patients' understanding and recall of the pictographic instructions were assessed. Pictograms were tested with 525 patients at the time of dispensing; 47 of these patients were also seen at short-term follow-up (the day after dispensing). Most of the pictograms tested achieved the European Commission standard for comprehension of greater than 80%, but were slightly below the American National Standard Institute criterion of greater than 85% comprehension. The use of pictograms caused a moderate increase in workload for the health care providers. Concludes that the use of a pictographic storyboard was valuable for medication counselling in a humanitarian aid setting; however, the use of pictograms increased the workload of the health care providers who supplied the counselling. (18 refs.)