This report describes a 2.8-year-old Swiss Braunvieh heifer with conjunctival changes as the lead clinical signs of malignant lymphoma. The heifer was referred to our clinic because of conjunctivitis that did not respond to treatment with antibiotics. The patient had bilateral lacrimation, severe swelling of the third eyelids and prolapse of the conjunctivae, which were erythematous and covered with haemorrhagic crusts. A clinical examination revealed enlarged prescapular and prefemoral lymph nodes. Based on cytological examination of a fine needle aspirate from a prescapular lymph node, a tentative diagnosis of malignant lymphoma was made. The heifer was euthanased and a postmortem examination carried out. The conjunctival lesions consisted of diffuse multifocal nodules of varying size. There was generalised lymphadenopathy and beige nodules were seen in several internal organs. Histological and immunohistological examinations confirmed the diagnosis of multicentric leukosis characterised by T-cell lymphoblasts, which had also infiltrated the conjunctivae. Examination of a blood sample for enzootic bovine leukosis virus yielded a negative result.