ABSTRACTObjective. A 42-days feeding trial was carried out to evaluate the influences of differently thermal processed soybean meal on the broilers blood biochemical parameters. Materials and methods. A total of 200 male birds of Ross strain were allocated into five different diets formulated using differently heat-treated soybean meals, with ten birds per treatment and per replicate. Diets contained: raw soybean (controls), autoclaved for a short (121°C, 20 min; Aut1 group) or medium length period (121°C, 30 min; Aut2 group) soybean meal, micro-waved soybean meal (46°C, 540 Watt, 7 min; McW group) and browned soybean meal (120°C, 20 min; Brn group). Results. Blood serum metabolites showed that all treated diets presented lower lipid metabolism makers and higher protein metabolism markers. Broilers showed increased final body weight when fed heat-treated meals compared with control. Results suggested that thermal treatments altered the lipid metabolism in broilers that might originate a decrease in abdominal fat deposition. Conclusions. Comparison of the results for all the treated groups showed the Aut2 treatment is the most suitable method for soybean thermal treatment processing; in contrast, the Aut1 treatment had the closest results to the control group.