Although the myocardial phospholipid and fatty acid content have profound effects on the heart function, very little information is available on the effects of restricted maternal protein intake during pregnancy on the phospholipid profile and fatty acid content of the developing heart. The present study was therefore undertaken to examine the effect of pregnant dams fed diets containing either 180 (normal) or 90 g (low) casein/kg diet for 2 wks before mating and throughout pregnancy on myocardial phospholipid and fatty acid content of male offspring. While no changes in phosphatidylcholine and phosphatidylethanolamine were detected, increases in lysophosphatidylcholine, phosphatidylserine and sphingomyelin were seen in the hearts of offspring in the low protein (LP) group. Analysis of cardiac fatty acids revealed that while the saturated fatty acid (myristate, palmitate and stearate) levels were significantly reduced, the unsaturated fatty acid (linoleate, arachidonate and decosahexanoate) levels were significantly increased in the developing heart in the LP group. Furthermore, assessment of nuclear transcription factors involved in regulation of cardiac metabolism revealed a decrease in MEF-2C mRNA levels in the LP group, whereas an increase in the mRNA amount of PPARwas observed in this group. These results demonstrate that maternal LP diet can induce changes in the phospholipid profile and fatty acid content of the developing heart, which may have implications for metabolism of the neonatal heart.