Different variables have been associated with the development/ maintenance of contamination-related obsessive-compulsive disorder (OCD), although the relevance of these factors has not been clearly established. The present study aimed to analyze the relevance and specificity of these variables. Forty-five women with high scores on obsessive-compulsive contamination symptoms (n = 16) or checking symptoms (n = 15), or non-clinical scores (n = 14) participated in a behavioral approach/avoidance task (BAT) with a contamination-OCD stimulus. Vulnerability variables and participants’ emotional, cognitive, physiological and behavioral responses to the BAT were appraised. Results show that fear of illness was a relevant vulnerability variable specific to contamination participants (p = .001; η2p = .291). Contamination participants responded with significantly higher subjective disgust (p =.001; η2p = .269), anxiety (p = .001; η2p = .297), urge to wash (p < .001; η2p = 370), threat from emotion (p < .001; η2p = .338) and contamination severity (p = .002; η2p = .260) appraisals, and with lower behavioral approach (p = .008; η2p = .208) than the other two groups. Moreover, contamination participants showed lower heart rate acceleration (p = .046; η2p = .170) and higher contamination likelihood appraisals (p < .001; η2p = .342) than the non-clinical group. Urge to wash was predicted by state disgust (R2 change = .346) and threat from emotion (R2 change = .088). These responses were predicted by general anxiety sensitivity (R2 change = .161), disgust propensity (R2 change = .255) and fear of illness (R2 change = .116), but not by other vulnerability variables such as dysfunctional beliefs about thoughts (Responsibility and Overestimation of threat) or disgust sensitivity. State disgust, threat from disgust, anxiety sensitivity and fear of illness were found to be the most relevant variables in contamination symptoms.