Introduction: Some studies using ecological momentary assessment (EMA) have revealed an association between craving for cigarettes and relapse. It is therefore important to understand the correlates of craving during smoking cessation. Attentional bias to smoking cues is a potential correlate of craving, but it has not previously been assessed using EMA during smoking cessation. Methods: Smokers enrolled in a research smoking cessation study were offered the opportunity to take part in an EMA study. Volunteers carried around a personal digital assistant (PDA) for the first week of their quit attempt. They completed up to 4 random assessments (RAs) per day as well as assessments when they experienced a temptation to smoke and when they relapsed. Craving for cigarettes was assessed with a single item (1ﾖ7 scale). Attentional bias was assessed with a smoking Stroop task (a reaction time task) at every other assessment, as was self-reported attention to cigarettes. Results: Data were available from 119 participants. Across 882 assessments, participants exhibited a significant smoking Stroop effect. Linear mixed models revealed a significant between-subject association between craving and the smoking Stroop effect. Individuals with higher levels of craving exhibited greater attentional bias. The within-subject association was not significant. Similar results were obtained for the relationship between self-reported attention to cigarettes and attentional bias. Conclusions: Attentional bias can be assessed in the natural environment using EMA during smoking cessation, and attentional bias is a correlate of craving during the early stages of a quit attempt.