We studied sera of 371 consecutive new patients with systemic sclerosis (SSc; scleroderma) who were first evaluated during 1984-1988. All sera were tested for antinuclear antibodies by immunofluorescence staining using HEp-2 cells as substrate. We excluded 219 sera showing dark nucleoli and screened for antibodies to Th in the remaining 152 sera by immunoprecipitation of a 32P-labeled HeLa cell extract. Fifteen (4.0%) of 371 sera were anti-Th+. Anti-Th antibodies were present in 14 (8.4%) of 167 SSc patients with limited cutaneous involvement, in 1 of 167 with diffuse cutaneous involvement, and in 0 of 37 with SSc overlap syndrome. Among 244 controls with other connective tissue diseases, antiTh was detected in only 3 patients, all having primary Raynaud's phenomenon of <2 years duration. In the subgroup with SSc with limited cutaneous involvement, the 14 anti-Th+ patients had a significantly greater frequency of puffy lingers, small bowel involvement, and hypothyroidism, and a significantly lower frequency of arthralgia andor arthritis. Their cumulative survival rate from the time of onset of symptoms was lower than that for anti-Th-patients (78% versus 91% at 10 years), primarily due to 3 deaths from pulmonary arterial hypertension (2 from primary pulmonary hy-