Danger Ideation Reduction Therapy (DIRT) is a cognitive treatment package developed in the mid-1990s to treat obsessive-compulsive (OC) washing. DIRT is solely directed at decreasing threat expectancies and does not involve direct or indirect exposure. The effectiveness of the DIRT package for OC washers has been examined, and to date a number of publications, including two randomised controlled trials, support its efficacy. Recently, the DIRT package was modified to treat people with the OC checking subtype. In the current study, three adult OC checkers received DIRT in 12 to 14 individual 1-hr sessions conducted by a clinical psychologist. At post-treatment, substantial and clinically significant reductions in scores on a range of standardized outcome measures of obsessive-compulsive disorder symptom severity were apparent for all three participants. Crucially, these improvements were maintained at 4-month follow-up. Although further research is clearly warranted, these preliminary findings suggest that DIRT for checkers may prove as effective as DIRT for OC washers.