Background: Distressing intrusive images are frequently experienced by sufferers from chronic and acute pain. The images (Index images) are correlated with elevations in anxiety, threat, and a cognition that the imaged event might actually happen. The over-estimation that having a negative cognition about an adverse event will increase the probability of the negative event occurring - the likelihood bias - has been observed in a variety of psychological disorders. Preliminary research indicated this cognitive bias might occur in pain sufferers. Aims: To investigate the occurrence of a cognitive likelihood bias associated with imagery in acute and chronic pain sufferers, and to relate the postulated cognitive bias to psychological characteristics of participants, and four other important cognitive responses to their Index images. Method: Fifty-nine pain sufferers completed a newly developed questionnaire (Image-Event-Fusion-pain: IEF-p) to assess cognitive likelihood bias in pain sufferers. The internal consistency, reliability, factor structure and validity of the scale were evaluated. Psychological measures to assess anxiety, depression, PTSD symptoms, and levels of mental defeat were administered. Results: The IEF-p was found to be psychometrically robust with satisfactory test-retest reliability, good internal consistency, single factor structure and criterion validity. The IEF-p was significantly correlated with four key cognitive appraisals of the Index Images (responsibility, likelihood, premonition, and threat). Three of these correlations were independent of depression. High cognitive bias scores were significantly associated with elevated levels of anxiety symptoms, depression, PTSD symptoms, and mental defeat. Conclusion: Pain Index images were significantly associated with cognitive bias (IEF-p), increased threat levels, and raised estimate of the likelihood of imaged events actually occurring. The results indicate the prevalence of a cognitive bias associated with pain imagery cognitions, comparable to that established with intrusive cognitions in OCD, notably Thought-Action- Fusion.