The present study was designed to examine the effect of cigarette smoking and withdrawal on working memory. Participants included 15 smokers and 22 matched non-smokers. For both groups the N-Back Task (of working memory) was administered in two test blocks on each of two days. On one day, smokers were tested after >or=13 h abstinence; on the other day, testing began <or=1 h after smoking. Smokers inhaled one cigarette between the blocks on each test day. Results indicated that performance of smokers after >or=13 h but not <or=1 h abstinence was significantly less accurate than that of non-smokers. A within-subject comparison revealed that in the abstinence session, smokers had significantly longer response latencies (in the 2-back condition) and made more overall errors compared to the satiety session. Smoking between test blocks in the abstinence session did not significantly affect performance although it significantly reduced craving. These findings provide further evidence for a deficit in working memory associated with acute abstinence from smoking, which may contribute to the difficulty of smoking cessation.