The clinical manifestations of patients with systemic lupus erythematosus (SLE) and negative fluorescent antinuclear antibody have been well documented. This report describes 2 cases of antinuclear antibody-negative SLE with antibodies only to Ro (SS-A) and the previously unreported clinical manifestation of lupus interstitial pneumonitis. A review of all SLE patients from 1984-1986 with interstitial pneumonitis revealed that 10 of the 12 patients had antibodies to Ro (SS-A). The frequency of anti-Ro (SS-A) with interstitial pneumonitis in SLE patients suggests a possible association between the two.