Malignant mesothelioma of the tunica vaginalis is a rare but potentially fatal disease. Lack of characteristic clinical features and tumour markers makes the pre-operative diagnosis very difficult. A 54 year-old man with no history of exposure to asbestos presented with a short history of scrotal swelling and pain. Ultrasound revealed a suspicious nodularity involving his tunica vaginalis, suggestive of mesothelioma. Excisional biopsy revealed a malignant mesothelioma; hence the patient was treated with radical inguinal orchidectomy and hemiscrotectomy. We present a case of this rare tumour, its management and a review of the literature.