A prospective study of 100 consecutive admissions to a university neurology inpatient service was done to assess the prevalence and spectrum of autoimmune rheumatic disorders, most specifically Sjögren's syndrome (SS), systemic lupus erythematosus (SLE), and lupus anticoagulant (LA)-associated disorders. All patients underwent a physical exam (PE), a rheumatic disease questionnaire, and serologic testing (ANA, RF, and LA). The 100 patients consisted of 36 men and 64 women, aged 17 to 98 (mean 60) years and included 47 white, 45 black and eight other. Definite rheumatic diseases were found in 11%. These included three with previously undiagnosed SS and neurologic symptoms of seizures and dementia, psychiatric disease, and embolic cerebrovascular accident (CVA). Also present were three CVA patients with LA; one migraine patient with known SLE and LA; and one each with CNS Whipples disease, Behcet's disease, isolated CNS angiitis, and B27+ spondyloarthritis. With respect to SS questions and PE findings, three groups of patients were identified: --Questionnaire; +PE 14 patients, aged 33-81 (mean 73) years; 13 F, 1 M who were not further evaluated although significant seroreactivity was present in three (RF 2, LA 1). --Questionnaire; -PE 16 patients, aged 32-98 (mean 56) years; 13 F, 3 M. Four patients had further evaluation, diagnostic for SS in three of them (3/3 abnormal lip biopsies, 2/3 KCS, 2/3 anti-Ro). Another four had unexplained seroreactivity (ANA 2, RF 1, LA 1). --Questionnaire; +PE 12 patients, aged 24-77 (mean 54) years; 10 F, 2 M, not further evaluated although four had seroreactivity in the setting of idiopathic neurologic disorders.(ABSTRACT TRUNCATED AT 250 WORDS)