The present study was done to investigate the effect of olive oil and saturated fats on plasma leptin and lipoproteins. The total number was sixty male broiler chickens, were used in this study. The birds were divided into four equal groups. The first group served as control, the second group was supplemented with Palestine olive oil "monounsaturated fatty acids, MUFA", while the third one was supplemented with saturated fat. The fourth group was supplied with a mixture of MUFA "olive oil" and saturated animal fat (1:1 ratio). The supplements were given orally in ration, daily for ten successive days, number of each group (10 birds) were then slaughtered and the remained number (5 birds) were allowed to recover " Recovery group" for seven days. Blood samples were collected from all groups. MUFA-treated group (2^nd group) showed a significant decrease in plasma leptin levels than control group, while HDL concentrations were increased significantly as compared to saturated fat-treated group. No significant changes were recorded in total cholesterol and other lipoproteins concentration. Saturated animal fat-treated group (3^rd group) revealed highly significant increase in plasma leptin level and highly significant decrease in HDL as compared with other treated groups, while there was no significant changes in cholesterol and other lipoproteins. MUFA plus saturated fat-supplemented group (4^th group) caused a moderate increase in plasma leptin level as compared to control and MUFA-treated groups. There were no significant alterations in cholesterol, triglycerides, LDL and VLDL concentrations. The present study concluded that MUFA alone or in combination with saturated animal fat resulted in elevation of plasma HDL. This response seemed to be independent to leptin plasma levels in the treated chickens.