Twenty-one OCD sufferers with washing/contamination concerns took part in a controlled treatment trial at the Anxiety Disorders Clinic, University of Sydney. Eleven of the subjects received danger ideation reduction therapy (DIRT) over eight, 1 h weekly group sessions conducted by the second author. Ten subjects were placed on a wait list and did not receive DIRT or any other treatment. DIRT procedures were solely directed at decreasing danger-related expectancies concerning contamination and did not include exposure, response prevention or behavioral experiments. Components of DIRT include attentional focusing, filmed interviews, corrective information, cognitive restructuring, expert testimony, microbiological experiments and a probability of catastrophe assessment task. All subjects were assessed at pre-treatment, post-treatment and three-month follow-up using the Maudsley Obsessional-Compulsive Inventory, Leyton Obsessionality Inventory, Beck Depression Inventory and a Self Rating of Severity Scale. Changes from pre-treatment to after treatment (post-treatment and follow-up scores averaged) were significantly greater in the DIRT condition than in the control condition for all measures. No significant differences were obtained between groups on post-treatment to follow-up change on any measure. The implications of these findings for theoretical models of OCD and its management are discussed.