Although rarely studied, popular beliefs play a role in treatment compliance. In order to clarify this problem in the field of anti-infectious agents we sent a questionnaire to 200 patients and 100 nurses of the community hospital in La Chaux-de-Fonds, Switzerland. We tried to test the influence, in poor patient compliance, of wrong beliefs concerning side effects and drug elimination. Eleven and twenty percent of patients suffered at least once from an episode of "allergy" and from another possible side effect respectively. Fatigue, often mentioned, has not been proved being a side effect and allergy is vastly overdiagnosed. Almost 50% of patients believe that antibiotics remain in the organism for months. Nurses are more intolerant to antibiotics than patients. In order to gain some insight on the role of cultural differences, the same questionnaire was submitted to nurses of the Moubda hospital in Cameroun. Their answers are very different from those of their swiss collegues: less side effects and allergies are reported. Nevertheless 17% would refuse an antibiotic therapy in case of a severe infection as compared to only 8% of swiss nurses. The reason for theses differences warrants further study.