We studied 120 first-degree relatives (FDRs) of 25 systemic lupus erythematosus (SLE) probands and 59 non-genetically associated individuals who were in close contact with the SLE patients. A significantly greater frequency of antinuclear antibody (ANA) positivity was found among the FDRs than in the control group (p less than 0.01). No significant difference was found in ANA positive between the female and male FDRs. Articular complaints or Raynaud's phenomenon were observed in 15% of the FDRs and in only 2% of the controls (p less than 0.05). Female FDRs had a greater number of rheumatic complaints than male FDRs (p less than 0.05) and a significant association was found between rheumatic complaints and ANA positivity (p less than 0.001) among the total FDRs.