Many people who complain of tinnitus say that the noises impair their mental concentration. This complaint was investigated by self-report (primarily the Cognitive Failures Questionnaire) and by means of five cognitive tasks, four presented via laptop computer and one given manually. The tasks measured performance under single- and dual-task conditions and included tests of sustained attention, reaction time, verbal fluency and immediate and delayed memory. Two groups of outpatients attending audiological clinics (tinnitus, n = 43; hearing impairment, n = 17) were compared with non-clinical volunteers (n = 32). The results replicated earlier findings that tinnitus outpatients report significantly more everyday cognitive failures than do controls. The tinnitus group responded significantly more slowly than the two control groups on the variable fore-period reaction time task under dual-task conditions. In general, comparisons between the groups on other tasks showed equivalent performance, but both clinical groups performed more poorly than non-clinical controls on verbal fluency. We conclude that cognitive inefficiency in tinnitus participants is related to the control of attentional processes, consistent with our earlier theoretical speculation about the nature of tinnitus complaint and with published findings on the effects of chronic pain on cognitive processes.