Compliance with therapeutic regimes is an important factor in treatment of chronic diseases often overlooked by therapists. In 123 out-patients with Crohn's disease the reliability in taking the prescribed therapy with salazosulfapyridine (SASP) was studied over an one year period in a special out-patient clinic. 81,3% of the patients took SASP regularly. Sex and age of patients, activity of disease and the intake of other drugs had no influence on the compliance. The patients were fully informed regarding the nature of the illness, the effect of the drug prescribed and the side-effects which may occur. We conclude that these factors; the periodical check up in a special ambulance and a close relation between patient and physician may improve compliance to therapy.