Hemorheology specialists believe that athletes of different sport fields have different hemorheological patterns. The aim of this study was to investigate the effect of sport field on hemorheological variables following acute aerobic exercise. Athletes were divided into three groups of 15 subjects (endurance runners: mean±SD: age 24.6±5.2 yr, BF% 6.8±1.6, BMI 21±1; football players: age 22.5±1.7 yr, BF% 7.61±1.6, BMI 22.3±1.4; karate players: age 23.1±3.5 yr, BF% 8.23±3.1, BMI 23.7±2.4) performed 30-min. exercise on a cycle ergometer at 85% maximal heart rate. Blood samples were collected before, immediately after the exercise and 30 min. after the recovery. Independent one-way ANOVA was used to investigate the effect of sport field on hemorheological parameters and analysis of variance with repeated measures was used to investigate the effect of exercise and recovery on hemorheological parameters. Significant differences in plasma and blood viscosity were observed following the exercise and recovery (p<0.05) and karate players had the highest viscosity. Plasma and blood viscosity increased after the exercise and decreased after the recovery.