OBJECTIVES: International evidence has shown that women have a worst quality of life than men. Frequently we make comparisons between gender groups using tools like SF12 V2 but less often we evaluated whether there is bias in these comparisons. The objective of this study was to evaluate the degree of comparability (invariance) of SF 12 V2 between men and women in chilean population. METHODS: Invariance analysis based on categorical Confirmatory Factor Analysis (CFA) of SF12 V2 using Chilean National Health Survey 2010 (n=5434). First we did a categorical CFA for the men and women separately, every model was evaluated with the recommended goodness of fit index (RMSEA<0.05; CFI≥0.95; TLI ≥0.95). Afterward using a multigroup categorical CFA we estimate four sequential invariance models for men and women. The models are: configural (same structures in both group, metric (same factor loadings between groups), scalar (same thresholds of categorical indicators between groups) and strict (same residual variance for each indicator between groups). Every model was a restrictive version (nested) of the previous one. We evaluate each of these models separately and compared with the previous one, based on the differences of a goodness of fit index (CFI variation = 0,01)