This is a multicenter, randomized, double-blind, parallel-group, placebo-controlled study to evaluate the efficacy and safety of trazodone hydrochloride prolonged-release tablets for treatment of depression in Chinese population.

Inclusion Criteria:

1. Age between 18 and 65, males and females, outpatients or inpatients;
2. Single episode or recurrent depression according to DSM-IV (Version 4) criteria;
3. Scores > 18 on 17-item HAM-D at screening and baseline visits with a decrease not exceeding 20% between the two visits;
4. Symptoms of depression for at least 1 month;
5. Patients or their dependents/guardians providing signed informed consent forms.

Exclusion Criteria:

1. Serious suicide attempts (≥ 3 on item 3 'Suicide' of HAMD);
2. Depressive episode, with psychotic symptoms;
3. Refractory depression;
4. Depressive episode secondary to other mental or physical disorders;
5. Bipolar disorder;
6. Significant reduction in body weight and malnutrition induced by major depression;
7. Serious or unstable heart, hepatic, renal, endocrine and hematologic disease or malignant tumors;