A national survey was conducted in a representative sample of the general French population in order to assess antidepressant non compliance frequency and the factors that influence it. Two types of noncompliance were taken into account: 1) the premature interruption of the treatment; 2) the omission of doses. Data were collected by phone interview. Results show that 36.9% of the 423 included subjects (who represent 4.3% of the sample) were noncompliants (15.4% by treatment interruption and 21.5% by dosage modification). The two types of noncompliance have different risk factors. Treatment interruption was more frequent for patients with high level of schooling (OR = 2.5), in case of multiple take regimens (OR = 3), when the physician did not informed the patient about treatment (OR = 3.3) and when the patients' sources of information were exclusively non medical ones (OR = 3.7). Dosage modification was more frequent in female (OR = 2.1), when the treatment duration exceeded six months (OR = 2.5) and when the prescriber did not communicate with the patient relatives (OR = 1.8). The information delivered by the physician about the duration of the treatment was associated with the two types of compliance but with an opposite effect. This information has a protective effect on treatment interruption (OR = 0.5) but increases the risk of dosage modification (OR = 1.1).