This study study was conducted to compare welfare indicators and some serum biochemical parameters of two different slow-growing genotypes (Hubbard S757; S757 and Hubbard Grey Barred JA; GB-JA) under organic housing system. A total of 240 day-old chicks were allocated randomly into 2 experimental group with 6 replicates and 20 chicks was reared in each replicate. The tonic immobility was a significant difference between genotypes and sex at 10 and 14 weeks, respectively (P < 0.05). Overall duration of tonic immobility was similar (P > 0.05) in genotypes and sex. The effect of sex was significant for width of tarsometatarsus at the joint with tibiotarsus; males had greater fluctuating and relativite asymmetry than females (P < 0.05). There were positively correlations between fluctuating and relative asimetry values of the third phalanx of the mid toe length and the fourth phalanx of the outer toe length from specific feet trait measurements. Serum cholesterol and uric acid had significant differences between genotypes (P < 0.01). Cholesterol levels was significantly (P < 0.01) higher in male than in female slow-growing broiler. It is concluded that slow-growing genotypes and sex had no effect on measures of welfare, such as the fluctuating asymmetry, relativite asymmetry, tonic immobility and rectal temperatures.