Objective. Investigate the effects of L-carnitine as a potential means of reducing the incidence of ascites in broilers and its relationship with physiological and biochemical paramaters. Material and methods. One-day-old 300 male broiler chicks (Ross 308) were used in the trial. The group without L-carnitine supplementation (0) was assigned as control and the groups that received 100, 150, 200 and 250 mg/L L-carnitine supplementation in water were assigned as treatment groups. The trial was completed in 35 days. Results. L-carnitine supplementation did not have any significant effect on live weight gain, feed consumption, water consumption and feed conversion ratio. Levels of blood plasma and hemogram parameters HDL, Triglyceride, CK, RBC and MCH were significantly affected by L-carnitine (p<0.05). Blood gas parameter pH value was significantly affected by L-carnitine supplementation in the broilers with ascites. Blood gas pH value significantly increased with 100 mg/L L-carnitine supplementation compared to that of control (p<0.05). While blood pH was 7.21 in the animals with ascites, it was determined as 7.48 in healthy animals. Concentrations of SO2 and ctO(2) were higher in healthy animals, while ctCO2P and hemoglobin concentrations were higher in ascitic animals (p<0.05). Conclusions. Ascites mortality rates starting from the control group were calculated respectively as %; 20.00, 18.33, 26.67, 28.33 and 28.33%. 76.71% of total ascites deaths were in the 5th week. It was concluded that low doses of L-carnitine supplementation may have positive effects in the broilers grown at high altitude.