The charts of 150 consecutive patients found to have antibodies to Sm, ribonucleoprotein (RNP), or both were examined to determine these antibodies' possible associations with certain clinical conditions as well as their diagnostic specificities. Patients with anti-Sm were more likely to have renal disease and antibodies to double-stranded DNA, single-stranded DNA, and nuclear protein than were patients with anti-RNP. No clinical associations were found for anti-RNP. Although most of the patients with antibodies to Sm, RNP, or both had systemic lupus erythematosus, some had other diagnoses, including cutaneous lupus, drug-induced lupus, rheumatoid arthritis, juvenile arthritis, mixed connective tissue disease, Raynaud's disease, progressive systemic sclerosis, miscellaneous rheumatic and nonrheumatic diseases, and undifferentiated connective tissue disease syndromes. These findings suggest that these antibodies may be associated with some diseases, but are not disease-specific.