OBJECTIVE To describe, for the first time, the occurrence of a large cyst in the orbital lobe of the lacrimal gland in association with marginal zone B-cell MALT lymphoma in three female patients, two of whom also had primary Sjögren's syndrome. METHODS Retrospective case note review. RESULTS Three female patients, aged 35, 41 and 47 years, presented with progressive proptosis caused by an enlarging cyst within the orbital lobe of the lacrimal gland. Two of the patients had primary Sjögren's syndrome. Excision of the cyst and part of the lacrimal gland revealed marginal zone B-cell lymphoma of mucosa-associated lymphoid tissue (MALT) type within the gland or wall of the cyst in all cases. The cysts were partially lined by ductular epithelium. One patient had systemic lymphoma, was treated with chemotherapy and remains in remission one year later; the other two had disease apparently confined to the lacrimal gland and are disease-free at 9 months and at three years after local irradiation, respectively. CONCLUSIONS To our knowledge, these are the first reported cases of cysts affecting the orbital lobe of the lacrimal gland in patients with B-cell MALT lymphoma of the gland. Although cystic changes have been described in other exocrine glands, lung and thymus in patients with Sjögren's syndrome, this association has also not been described in the lacrimal gland before.