Startle eyeblink modification was measured during a degraded stimulus continuous performance test following both smoking and overnight abstinence among student smokers to measure the effects of smoking on both early and late attentional processes. A group of nonsmokers was tested twice without nicotine manipulation. A startling noise was presented either 240 or 1200 ms following target and nontarget stimuli presented during the task. Startle inhibition at 240 ms was greater following targets than nontargets following smoking and during both nonsmoker tests, but this attentional modulation was absent following abstinence. At the 1200-ms probe position, target and nontarget stimuli produced nondifferential inhibition during both tests for both groups. Abstinence among smokers produced reliably lower vigilance performance compared to ad lib smoking. The results indicate that smoking abstinence affects the early stages of stimulus processing.