Research suggests that the human attentional system is biased towards emotional events in the environment. This attentional bias is believed to be an adaptive function that can provide survival benefits for the organisms that possess it. Dispositional optimism is a trait defined as a general expectation that good things will happen in the future. This trait has received interest as an adaptive trait that has a multitude of psychological and physical benefits for the individuals who exhibit it. The aim of this study is to examine whether there is a difference in the attentional bias towards happy and angry facial expressions based on level of dispositional optimism using the dot-probe paradigm. Thirty-two psychologically and neurologically healthy females (mean age = 26.5, SD = 5.8) participated in the study. They completed a questionnaire measuring dispositional optimism and performed the dot-probe task in a laboratory setting in the University of Skövde. In the dot- probe task a short exposure (100 ms) of photographs depicting happy, angry and neutral facial expressions was used as emotional cues. A general bias towards happy faces across all participants was detected. Also, a clear trend towards an interaction between DO and AB to emotional faces was found in the group high in DO displaying and AB towards happy facial expressions. This study implies that for the psychologically and neurologically healthy population, a fast operating and automatic AB for positive stimuli exists, moreover, this AB may be modulated by individual differences in DO.