Evidence-based guidelines have been developed in several countries to assist GPs in daily practice. Cultural factors play a role in clinical decision-making. This study demonstrates that authors of guidelines are often not aware of these cultural influences. Once confronted with differences between guidelines from other countries, the guidelines' authors provide scientific arguments as well as cultural arguments. Differences in selection of evidence between guidelines are striking and need more research. Objective - To compare four recent guidelines on uncomplicated cystitis and to examine how cultural factors may have affected recommendations. Design - Descriptive study with a qualitative analysis of authors' reasons for recommendations. Material - Guidelines for general practitioners published 1999-2000 from Germany, The Netherlands, Norway, and Belgium on diagnosis and treatment of uncomplicated cystitis. Opinions of the guideline authors on the influence of local factors on the recommendations were collected before and after feedback on the differences between the guidelines. Results - Few cited references were shared between the guidelines, and recommendations differed substantially, especially on diagnostic strategies and referral criteria. The authors attributed parts of the differences to local factors. German and Belgian authors stressed the need for safety in their diagnostic and therapeutic approach, while Dutch authors felt confident in their gatekeeper role and the Norwegian authors mainly relied on "the evidence". Dutch and Belgian authors perceived patients to hold power, German authors referred to the power of the sub-specialists, while the Norwegians aimed to share power with the patient through a patient-centred approach. Conclusion - There are substantial differences even between high-standard guidelines on the same well-defined clinical entity. The selection of literature data, and diagnostic and therapeutic recommendations, seemed to be influenced by such cultural aspects as habits, the patient's expectations, and the structure of the healthcare system. [ABSTRACT FROM AUTHOR]