Fifty-eight patients with progressive systemic sclerosis (PSS) were evaluated clinically and by biopsy of the minor salivary glands of the lips for the presence of Sjögren'S syndrome. Clinical findings included dry eyes in 38%, dry mouth in 32%, parotid enlargement in 4%, and an abnormal Schirmer'S test in 34%. Histologic changes in lip biopsies included lymphocytic infiltrates characteristic of Sjögren'S syndrome in 17 individuals (29%). In 19 (33%) there was periglandular and intraglandular fibrosis (PSS-fibrosis) without significant inflammation, an alteration characteristic of PSS per se. In the remaining 22 patients (38%) with PSS, no abnormality was found. Of those with PSS and Sjögren'S syndrome, 53% had serum antibodies to SS-A and/or SS-B, while only 1 patient with a normal biopsy had either of these antibodies. Anti-SS-A and anti-SS-B were not detected in patients with glandular fibrosis alone. The mortality rate of the PSS-fibrosis group was higher due to a variety of severe internal manifestations related to PSS. Antibodies to SS-A and SS-B are useful serologic markers of the presence of Sjögren'S syndrome in patients with PSS.