Subungual glomus tumours are rare benign hamartomas arising from the arterial end of the glomus body (an arteriovenous shunt related to thermoregulation). A combination of clinical examination, Color-Doppler ultrasonography and magnetic resonance imaging (MRI) is used to support the diagnosis confirmed by histology. A 45 year old male patient with a three-year-old swelling of the proximal thumbnail presented himself at the Surgery Department. A slightly bluish nail plate and tenderness under the thumbnail were evident at clinical examination. He suffered the classic trilogy of sensitivity to pain, pressure and temperature of the thumb lesion. Ultrasound and MRI revealed the presence of a small oval-shaped mass with hypervascularisation. All these elements reinforced the assumed diagnosis of a glomic tumour. The patient underwent excisional surgery under local anaesthesia. Histological examination confirmed a typical glomus tumour. Postoperative follow-up was uneventful and all symptoms disappeared immediately after surgery. Whenever a patient presents suffering from a reddish-purple, tender lesion, usually located at the extremities and especially in the nail bed, with paroxysmal pain and cold-sensitivity, a glomus tumour should be investigated. Surgical excision is the treatment of choice and is commonly resolutive.