There is a lack of knowledge regarding the long-term effect of evidence-based CBT/ ERP treatment for OCD that is delivered in routine clinical care. The aim of this study was to examine the long-term effectiveness of behavioral treatment for OCD in a Norwegian general outpatient clinic. In the current study, 62% (N = 40) of the original patients treated in a previously published study of group ERP for OCD were re-evaluated an average of eight years after completing the original treatment. This is the longest follow-up study that has been conducted for OCD patients treated with group ERP. There was a significant reduction in symptoms from pre- to post-treatment measured with the Yale-Brown Obsessive Compulsive Scale (Y-BOCS), the Spielberger State Anxiety Inventory (STAI-S) and the Beck Depression Inventory (BDI). The gains were in average maintained from post-treatment through extended long-term follow-up. Fifty percent of the participants experienced either a clinically significant improvement (10%) or recovery (40%) in OCD symptoms at extended long-term follow-up. This suggests that many patients receiving general outpatient mental health clinic based group ERP for OCD maintain gains over the long-term.