Ethmoid sinus adenocarcinoma with orbital invasion is distinctly uncommon. This case presented with epiphora, whereas proptosis and decreased ocular motility were later signs. Treatment was delayed for 4 months, while misdiagnoses like dacryocystitis and thyroid eye disease were entertained. Even an incisional biopsy was not sufficient for a conclusive diagnosis and adenomatous differentiation was only present in a small proportion of tissue available after an excisional attempt. The aggressive behaviour including this patient's death of metastatic disease, underlines the importance of considering secondary invasion from a sino-nasal malignancy in uncharacteristic orbital disease.