Genetic parameters concerning weight of abdominal fat pads were determined for a randombred layer-type population. Progeny by the upper (U) and lower (L) 10% of the sires with respect to weights of fat pads were compared. Cellularity measures were made of the fat pads from random samples of the two groups of progeny. Progeny of U sires had fat pads numerically heavier than those of progeny by all sires. However, progeny of L sires had fat pad weights similar to those of all sires. Heritability estimates of abdominal fat pad weight, as calculated from half-sib correlation and regression of offspring on sires, were .29 +/- .36 and .27 +/- .06, respectively. Genetic estimates indicated fat pad weight to be highly correlated with growth but essentially uncorrelated with egg production. Progeny of the L and U sires had the same number of adipocytes, but progeny by U sires had larger adipocytes than progeny by L sires.