We investigated how patients with obsessive-compulsive disorder (OCD) were affected by coronavirus disease of 2019 (COVID-19)-related stress over the long term compared to healthy individuals. We explored how the pandemic affected changes in obsessive-compulsive symptoms and their contributing factors. The study included 100 patients with OCD and 100 sex-matched healthy controls whose sociodemographic and clinical information were gathered. Participants in the study were recruited between December 2021 and May 2022 from individuals attending to the outpatient clinics of the University Department of Psychiatry. The Depression Anxiety Stress Scale-21, Perceptions and Attitudes Towards COVID-19 Questionnaire, COVID-19 Compliance with Prevention Measures Scale, and COVID-19 Stress Scale were used in this study. Patients were assessed using the Yale-Brown Obsession Compulsion Scale based on their conditions before and during the pandemic. Patients with OCD perceived COVID-19 disease as more dangerous and contagious (respectively P = .01, P = .01) compared to the controls. Fifty percent of the patients with OCD experienced an increase in symptoms. Disease severity was increased in mild and moderate OCD, while no significant change was found in severe OCD. Perceiving COVID-19 disease as more dangerous (P = .031), COVID-19-related traumatic stress (P = .013), compulsive control (P = .022), xenophobia (P = .005), and COVID-19-related thoughts (P = .008) were more frequent in OCD patients with clinical worsening. In regression analysis, younger age (OR: 0.95, 95% CI (0.91-0.99)) and higher levels of COVID-19-related stress (OR: 1.03 95% CI (1.01-1.05)) are associated with worsening OCD symptoms. Patients with OCD were adversely affected by the COVID-19 pandemic. Close monitoring of patients with OCD during the pandemic is recommended.