OBJECTIVES: We investigated the long-term tolerability of escitalopram in Korean adolescents. METHODS: The subjects were 37 adolescents, who had been diagnosed with depressive disorder in accordance to DSM-IV. Clinical effectiveness was assessed by Clinical Global Impression-Improvement (CGI-I) scale at the final follow-up visit. Tolerability was assessed through a medical record of the reason for discontinuation of escitalopram and documented adverse events. RESULTS: The mean duration of treatment was 78.1+/-89.5 days, and the mean dosage was 10.0+/-4.4mg/day. Out of the total 37 patients, two (5%) patients sustained use of escitalopram. Twelve patients (32.4%) discontinued use of escitalopram due to target symptom remission, and 23 patients (61.9%) due to insufficient efficacy. Six patients (16.2%) had at least one documented adverse event. However, no suicidal ideation or self-injurious behavior was reported. Significant differences in clinical symptom improvement efficacy were seen between the patients who were receiving escitalopram for less than 8 weeks (4.3%, 1/13) and those for more than 8 weeks (92.9%, 13/14). There was no significant difference between the tolerability of monotherapy compared to the concomitant use group. CONCLUSION: The results of this study suggest that long-term use of escitalopram may result in superior efficacy than short-term use, and is tolerable in Korean adolescents with depression.