Extranodal natural killer/T-cell lymphoma (ENK/TCL) is most often in the nose or the nasopharynx but can present elsewhere. We report a rare case of ENK/TCL that presented as swelling of an upper eyelid without ocular involvement. A 76-year-old man visited our hospital with a swollen lesion of the left upper eyelid which had appeared 2 months earlier. A biopsy of the upper eyelid revealed slight perivascular and periadnexal infiltration of mononuclear cells with dermal edema. Treatment with oral prednisolone at a dosage of 20 mg/day decreased the eyelid swelling. However, 5 months later, exacerbation of the swelling and nasal congestion were observed. A second biopsy of the upper eyelid revealed a diffuse dermal infiltrate composed of mononuclear cells with an angiocentic growth pattern. Immunohistochemical studies and in situ hybridization showed natural killer-lineage antigens (CD56, granzyme B, and T-cell intracellular antigen 1) with expression of Epstein-Barr virus. These findings lead to the diagnosis of ENK/TCL. We treated the patient with radiation therapy (50 Gy) and 3 courses of a regimen including dexamethasone, carboplatin, etoposide, and ifosphamide. This case suggests that ENK/TCL can present with swelling of an upper eyelid as the primary sign of the skin lesion. Swelling of an upper eyelid should be considered in the differential diagnosis of ENK/TCL.