Two cases of primary Sjögren's syndrome revealed by dementia are reported. The patients had progressive or subacute memory dysfunction and psychiatric disorders with depression and delirium. The diagnosis of Sjögren's syndrome was established by biopsy of the minor salivary glands. Both patients were treated with corticosteroids. The neuropsychiatric symptoms improved dramatically in one case and remained unchanged in the other case. Dementia in Sjögren's syndrome seems to be without aphasia, apraxia or agnosia, and associated with psychiatric features, particularly depressive symptoms, thus including some characteristics of subcortical dementia. Diagnosis may be difficult because, as shown in our cases, symptoms of ocular and buccal dryness can be absent. Salivary gland biopsy can be useful in the evaluation of patients with dementia of undetermined etiology.