A number of studies have shown that patients with obsessive-compulsive disorder do not universally regard their obsessions as either senseless or unlikely to happen. This is of particular significance for the current cognitive-behavioural model of OCD, which is based on the notion that obsessions are ego-dystonic. This study examined the appraisal of obsessions by a group of OCD patients (n=63). Participants completed a paper and pencil task in which they had to appraise a range of intrusive thoughts and contamination fears on two variables: senselessness and likelihood to happen. The results suggest that the appraisals may vary according to the content of the obsessive thought. Contamination obsessions were judged less senseless and more likely to happen than obsessions concerning aggressive and sexual themes. A number of variables, which may play a role in these appraisals, are discussed and the methodological limitations of the study are examined.