BACKGROUND: This study investigates whether cognitive impairment is evident in inpatients diagnosed with Major Depression (MD) following electro-convulsive therapy (ECT), and if so, whether it is independent from depressive symptomatology. METHODS: Speed of information processing was measured using the inspection time (IT) task. IT was compared between twelve inpatients diagnosed with MD receiving ECT and twelve age-, gender-, verbal IQ-, and depression and anxiety severity matched control inpatients diagnosed with MD not receiving ECT, over four testing sessions (prior to ECT, following one ECT session, following the completion of an ECT block, and 4 to 6 weeks after the ECT block (follow-up)). RESULTS: The mean IT score for the inpatients diagnosed with MD who received ECT slowed significantly from the first ECT to immediately after the ECT block, and was significantly faster at follow-up. The mean IT score of the inpatients diagnosed with MD not receiving ECT gradually but significantly became faster over the entire equivalent time period. LIMITATIONS: Small sample sizes. CONCLUSIONS: ECT temporarily slows information processing speed in MD patients, independent of depression symptomatology.