Vulvar intraepithelial neoplasia (VIN) is a pre-malignant condition of the vulvar skin that is found in 50% to 70% of patients with vulvar squamous cell cancer and is regarded as a precursor of vulvar tumors. Thus far, treatment remains lesion- and patient-specific. Here, we describe a VIN patient who presented with a 15-month history of large lesions in the bilateral labium, associated with human papillomavirus infection. The lesions were inappropriate for surgical excision and laser ablation because of their size; therefore, they were treated with photodynamic therapy and concurrent topical 5-aminolevulinic acid hydrochloride. The patient showed no recurrence throughout 2 years of post-treatment follow-up, and reported only slight pain during treatment. Moreover, no significant side effects or scarring were detected. Thus, we conclude that photodynamic therapy can be a useful alternative treatment for large VIN in the bilateral labium that cannot be excised or ablated.