Depression is one of the most frequent comorbid psychiatric disorders identified in patients with neurological disorders. The prevalence rates range between 20 and 50% of patients with stroke, epilepsy, multiple sclerosis, and Parkinson's disease. Despite these relatively high prevalence rates, depression remains underrecognized and undertreated in these patients. And yet, depression accounts for poor quality-of-life ratings and has a negative impact on the recovery from neurological symptoms. In this article, we review the epidemiological and clinical characteristics of mood disorders in patients with multiple sclerosis, Parkinson's disease, stroke, and epilepsy, and focus on the impact mood disorders have on the quality of life of these patients and on their recovery from their neurological deficits.