OBJECTIVE: To compare two methods of assessing costs of pharmacological treatment of CVI: based on a resource utilization questionnaire and on a global estimation of expenditure declared by patients. METHODS: The study of costs associated with CVI in Poland was performed on a representative sample of 1000 people over 18 from the general population. In patients suffering from CVI, data concerning all the costs related to this illness were collected by trained interviewers. Among the many questions, patients were asked about oral and local medicines consumed (in units), as well as about their own global estimation of monthly expenditure on treatment. Finally, the costs calculated in the two different ways were compared. Different cost groups: compression therapy, surgical and cosmetic operations, diagnostic tests, hospitalisation and indirect costs were measured in the traditional way (and not compared). RESULTS: 136 people received oral treatment for CVI. The average global estimation of monthly expenditure on oral treatment was €16.82. Monthly expenditure based on resources consumed was equal to €6.12. Local medicines were used by 186 people. The average global estimation of monthly expenditure for local treatment was €9.32 compared to €3.08 when calculated on resource utilization basis. CONCLUSIONS: The patients' perception on how much they spend on their treatment differs to a great extent from the cost of medicines calculated on a resource utilisation basis. The cost of treatment can be assessed accurately on a basis of a well designed resource utilisation questionnaire and unit cost.