In the present study it is aimed to investigate the effects of different isocaloric syrups on obesity and also to determine the consumption preference of the rats. Fiftyfour, 3 weeks-old, Wistar Albino rats (27 female, 27 male) were included to the study. Rats were divided into 3 groups as control (n=18; 9F, 9M), sucrose (n=18; 9F, 9M) and HFCS (n=18; 9F, 9M) groups. All of the groups were fed up with standart chow, in addition tap water to Control group, sucrose to Sucrose group and HFCS sloution to HFCS group were given. Mixtures were prepared at 15% concentration by mixing with tap water. Rats were fed up for six months and their weights were monitored. At the end of the study, serum triglyceride, total cholesterol, HDL-cholesterol, LDL-cholesterol and VLDL-cholesterol levels were analysed and also liver and abdominal aorta were histopathologically estimated. Male and female rats in both sucrose and HFCS groups, while significantly decreased chow consumptions were detected, sugar solutions and calori consumptions, levels of serum total cholesterol and HDL-cholesterol were significantly increased. In Sucrose group significantly higher consumption of liquid, chow and calori were detected compared to HFCS. However, weight gain was significantly high in sucrose group in male rats, weight gain was significantly high in HFCS group in female rats. Whereas sucrose consumption caused increase in LDL-cholesterol, HFCS consumption caused decrease in LDL-cholesterol. In conclusion, it can be expressed generally that there is no significant difference between sucrose and HFCS solutions about inducing obesity and affecting negatively on blood lipid profile however there have been different effects between these two solutions which may be related to gender. To observe significant effects, it should be useful to restudy with more concentrated sucrose and HFCS solutions. [ABSTRACT FROM AUTHOR]