Background: Vulvar Paget disease is an extremely rare skin disorder, which is most common in postmenopausal women. Most vulvar Paget disease cases are noninvasive; however, it may be invasive or associated with an underlying vulvar or distant adenocarcinoma. The current treatment of choice for noninvasive vulvar Paget disease is wide local excision, which is challenging because of extensive intraepithelial spread and may cause severe morbidity. Recurrence rates are high, ranging from 15% to 70%, which emphasizes the need for new treatment options. Imiquimod, a topical immune response modifier, has been shown to be effective in a few studies and case reports, and is a promising new treatment modality. Objective: To prospectively investigate the efficacy, safety, and effect on quality of life of a standardized treatment schedule with 5% imiquimod cream in patients with noninvasive vulvar Paget disease. Study Design: The Paget Trial is a multicenter prospective observational clinical study including 7 tertiary referral hospitals in the Netherlands. A total of 24 patients with noninvasive vulvar Paget disease were treated with topical 5% imiquimod cream 3 times a week for 16 weeks. The primary efficacy outcome was the reduction in lesion size at 12 weeks after the end of treatment. Secondary outcomes were safety, clinical response after 1 year, and quality of life. Safety was assessed by evaluation of adverse events and tolerability of treatment. Quality of life was investigated with 3 questionnaires taken before, during, and after treatment. Results: Data were available for 23 patients, 82.6% of whom responded to therapy. A complete response was reported in 12 patients (52.2%), and 7 patients (30.4%) had a partial response. A histologic complete response was observed in 10 of the 12 patients with a complete response. Patients experienced side effects such as fatigue (66.7%–70.9%) and headaches (16.7%–45.8%), and almost 80% needed painkillers during treatment. Eight patients (34.8%) adjusted the treatment protocol to 2 applications a week, and 3 patients (13.0%) stopped treatment because of side effects after 4 to 11 weeks. Treatment improved quality of life, whereas a slight, temporary negative impact was observed during treatment. Two patients with a complete response developed a recurrence within 1 year after treatment. Follow-up showed 6 patients with a noninvasive recurrence after a median of 31 months (14–46 months) after the end of treatment. Conclusion: Topical 5% imiquimod cream can be an effective and safe treatment alternative for noninvasive vulvar Paget disease, particularly when compared with treatment with surgical excision.