The present work was an attempt to study on effects of fish oil (omega-3) and L-carnitine on some hematological parameters such as the red blood corpuscles (RBCs), white blood cells (WBCs) and platelet parameters. Rats were divided into four groups, rats maintained on a normal diet for 4 weeks, rats maintained on a high sucrose (60%) diet, and two other groups received 4% omega-3 in the diet and oral administration of 500mg/Kg body weight L-carnitine. Statistical analysis revealed that WBCs count, RBCs count, hemoglobin (Hb), packed cell volume (PCV) and mean corpuscular hemoglobin concentration (MCHC) were significantly increased in sucrose enrich diet group. Surprisingly L-carnitine when omega-3 significantly (p< 0.01) lowered WBCs count. L-carnitine caused leucopenia but omega-3 did not. L-carnitine also lowered RBCs count and Hb content, while, omega-3 didn’t change these parameters. Platelet was increased in sucrose group, while, omega-3 treatment returned was much or less similar to that of the control group. A significant decrease of mean platelet volume was also detected in L-carnitine group, but, omega-3 didn’t affect it significantly. In conclusion, the results suggested that L-carnitine rather than omega-3 should be taken in a low doses they may cause leucopenia and anemia.