This study compared the clinical usefulness of the peripheral pattern detected in immunofluorescent antinuclear antibody (ANA) testing with anti-DNA measured by the modified Farr technique. 48 patients with active or inactive systemic lupus erythematosus (SLE) were studied at one point in the course of their disease. There was no association between titres of serum giving a peripheral ANA pattern (tp-ANA) and anti-DNA values. Tp-ANA did not correlate with activity of SLE. In contrast with this finding, anti-DNA correlated with severity of renal disease, decreased serum complement, and number of SLE criteria. In a separate group of 9 patients with flare-ups of SLE, tp-ANA and anti-DNA fell as disease activity was controlled. Nevertheless, these two parameters were independent of one another. It was concluded that tp-ANA did not accurately reflect anti-DNA or activity of SLE.