A study was carried out among asthmatic patients in order to determine their compliance to treatment and self-medication. Data collection used a self-administered postal questionnaire as tested in a previous study. The population under study included 450 asthmatic patients; 370 answered; their mean age was 47 +/- 16 yrs and 44% were men. An aerosol was the preferred route of administration (41%). Eighty two percent of the patients tended to reduce the doses following improvement; 80% claimed to know treatment for attacks; 90% had already been using an inhaler, although only 62% had been shown how to use one. Forty eight percent had already bought drugs without prescription, especially patients within the 25-34 yrs age group. This study is consistent with similar surveys performed in other populations. Improved quality of information about treatments and how to use drugs is higher in patients with chronic forms of asthma involving unpredictable acute attacks.