The effects of feeding rats a diet containing 0.2% added phytic acid for 5, 10, 15 and 20 days (groups II, III, IV and V, respectively) on lipid metabolism were studied. The animals in group I (controls) were fed Murigran, a complete feed (from Motycz) without added phytic acid. It was found that phytic acid lowered free fatty acid levels in the blood. Their average concentration was 0.745±0.05 mmol/L in group I, 0.625 ±0.05 in group II, 0.677 ±0.04 in group III, 0.590±0.04 in group IV and 0.599±0.02 mmol/L in group V. A significant decline in the triglyceride content in the liver also occurred under the influence of phytic acid: in group I 27.821±1.73 mmol/kg, in group II 22.012±2.05, in group III 24.420±1.48, in group IV 20.206±0.75 and in group V 22.101±1.40 mmol/kg. Phytic acid also increased the cholesterol content in whole blood serum (in group I 1.758±0.09 mmol/L, in group II 1.997 ±0.06, in group III 1.903 ± 0.08, in group IV 2.025±0.05 and in group V 2.001 ±0.05 mmol/L) as well as in the HDL fraction (in group I 0.514 ±0.03 mmol/L, in group II 0.652 ±0.03, in group III 0.639±0.05, in group IV 0.672±0.02 and in group V 0.636±0.03 mmol/L). These changes may be a consequence of the inhibitory effect of phytic acid on the absorption of elements from the digestive tract or they may result from the action of the inositol that is formed as the result of dephosphorylation of phytic acid.