Attention is typically impaired in depression and may play a role in risk for suicidal behavior. In this study, 66 non-patients, 83 depressed subjects with no past history of suicide attempt, 53 depressed subjects with one or more low lethality suicide attempts, and 42 depressed subjects with at least one high lethality attempt were compared on two computerized measures of attention, a continuous performance test (CPT) and a Stroop task. All subjects were medication free at the time of assessment. Attention was impaired in all depressed subjects but worse in those with a past history of suicidal behavior. CPT performance did not differ among the groups, but Stroop interference was significantly poorer in all depressed subjects relative to non-patients, and poorer still in high lethality suicide attempters relative to all other groups. Interference scores correlated modestly with subjective depression, functional level, suicide ideation, number of past suicide attempts, and lethality of past attempts. Depression-related impairments of attention, especially susceptibility to interference, are accentuated in those with a past history of suicidal behavior. Fundamental deficits in attentional control may play a role in risk for suicidal behavior, and may contribute to a variety of cognitive deficits in suicidal patients. Brain regions subserving attentional control, which overlap considerably with regions implicated in affective disorders, may be a useful target for studies seeking to characterize neuropsychological factors associated with suicidal behavior.