Effective treatments for obsessive-compulsive disorder (OCD) exist, however, many patients experience barriers to treatment. Internet-administered cognitive-behavioral therapy (iCBT), which has the potential to reduce these barriers, has recently been shown to be efficacious in the treatment of OCD. To date, only therapist-guided iCBT interventions have been studied for OCD. Self-guided iCBT, administered without a therapist, may help to further reduce barriers to treatment, particularly for those concerned about stigma or who are unlikely to engage in treatment with a therapist. The present article describes the results of two open-trial feasibility studies that examined the acceptability and preliminary efficacy of fully self-guided iCBT for symptoms of OCD. In both trials scores on the Yale-Brown Obsessive Compulsive Inventory-Self-Report and the Dimensional Obsessive Compulsive Scale reduced significantly over time and moderate to large effect sizes were obtained. In trial 1, 29% met criteria for clinically significant change at 3-month follow-up and in trial 2, 32% met criteria for clinically significant change at 3-month follow-up. These results indicate that self-guided iCBT may be an acceptable and effective treatment for some individuals with obsessive-compulsive symptoms.