Depression is a common disorder with painful symptoms and, frequently, social impairment and decreased quality of life. The disorder has a tendency to be long lasting, often with frequent recurrence of symptoms. The risk of relapse and the severity of the symptoms may be reduced by correct antidepressant medication. However, the medication is often insufficient, both in respect to dosage and length of time. The reasons for incorrect medication are many, with lack of adherence to treatment being the most important. Although some patients taking antidepressant medication experience side effects, this may not be the most frequent reason for immature discontinuation of treatment. Other reasons for decreased adherence have been investigated in recent years. The patient's beliefs about the disorder and beliefs about antidepressants, including lack of conviction that the medication is needed and fear of dependence of antidepressant medicine, have a great influence on adherence to treatment.