We studied 54 idiopathic Parkinson's disease (PD) patients with depressive disorders (DD) to compare the efficacy and the effect of treatment with sertraline in the usual formulation and in the liquid oral concentrate (LOC) formulation. After 6 months of sertraline treatment, the Hamilton Depression Rating Scale and the Montgomery and Asberg Depression Rating Scale showed a decrement (p<0.001, for both formulations). Parkinson's Disease Questionnaire scores improved (p<0.005 for usual formulation and p<0.001 for LOC formulation), as did Clinical Global Impression-Severity of Illness scale and Clinical Global Impression-Global Improvement scale scores (p=0.1, for both formulations). Mini Mental State Examination and Unified Parkinson's Disease Rating Scale motor subscores did not change. These results suggest that sertraline LOC may also be a useful treatment for DD in PD patients, especially for those with swallowing problems, and have significant benefit for quality of life, without worsening of parkinsonian features.