Background: The lack of an implicit measure for the obsessive-compulsive disorder symptoms limits its assessment to the traditional scales and inventories. Objectives: The aim is the construction of an instrument for the evaluation of obsessive-compulsive symptoms that is independent from examinee´s self-evaluation [i.e. the Implicit Association Test for obsessive-compulsive disorder (IAT-OCD)]. Methods: In order to build the IAT-OCD, we consulted (1) previous studies that employed the IAT for the evaluation of other psychiatric symptoms; (2) expert psychiatrists and psychologists with experience in the assessment and treatment of patients with OCD; and (3) patients with OCD themselves. Results: Specific verbal and visual stimuli were selected for each obsessive-compulsive symptom dimensions (contamination-washing, obsessions-checking, symmetry and hoarding). A software designed to measure reaction time in miliseconds (a proxy for implicit association) was developed. A final version of the IAT-OCD was then obtained. Discussion: The IAT-OCD expands the existing armamentarium to evaluate obsessive-compulsive symptoms, especially among those individuals who report badly about their symptoms.