An important determinant for achieving efficacy results in clinical practice comparable to those demonstrated in clinical trials is whether or not patients take their medication as prescribed. Recent studies have shown that 30–60% of patients do not take their medications as prescribed. Gaps between antidepressant prescriptions raise questions about the possibility of periods of nonadherence to medication in clinical practice. The purpose of conducting this study was to assess the likelihood of experiencing a gap of > 15 days between antidepressant prescriptions for patients with a depression-related diagnosis and to assess whether this likelihood varied across different antidepressants with tricyclic antidepressants and selective serotonin reuptake inhibitors. Episodes of antidepressant treatment were constructed using the Doctors' Independent Network general practitioner medical records database. For all antidepressant agents considered, approximately 50% of patients had a gap between prescriptions and 15–25% of patients had a gap of > 15 days between prescriptions, A significant proportion of patients in a general practitioner setting in the UK have gaps recorded of > 15 days between antidepressant prescriptions. Gaps between prescriptions raise the question of whether patients may be at risk for clinical consequences associated with nonadherence to therapy, such as reduced effectiveness or treatment interruption symptomatology.