Objectives: The aim of the present study was to investigate working memory impairments in individuals with major depressive disorder. Method: Twenty five patients with major depressive disorder according to DSM-IV criteria, were matched by gender, age and education with 25 normal controls. All completed Beck Depression Inventory and participated in two working memory tasks:“Paced Auditory Serial Adding Test (PASAT)” and “Wechsler Digit Span Scale”. Results: T-test for independent groups indicated a weaker function in both memory tests for depressed subjects compared to the control group (p< 0.001). Pearson correlation coefficient and regression analysis showed a significant negative correlation between function in working memory tests and the severity of depression (p< 0.001). Conclusion: Depression is associated with impairment of working memory, and the amount of impairment increases along with the increase in the severity of depressive symptoms.