The wide variety of commercial kits used to test antinuclear antibodies (ANA) by indirect immunofluorescence (IIF) makes comparison of data from different laboratories difficult. Data comparing the sensitivity and feasibility of the various kits are not available. Eight different methods using tissue section and monolayer substrates for evaluating serum ANA by IIF were compared using single pattern ANA-positive sera. A rationale for selection among these kits and guidelines for interlaboratory comparison is presented.