Significant intrafamilial correlations of left ventricular mass exist in first-degree relatives. However, the specific maternal and paternal influences on left ventricular mass of offspring remain unknown. We therefore evaluated familial aggregation of left ventricular mass by type of familial relation in two European populations. A random sample of 159 nuclear families (250 parents and 321 offspring) was investigated in Cracow, Poland, and Novosibirsk, Russia. The mean age of parents and offspring was 51.4 years and 25.1 years, respectively. Two-dimensionally guided M-mode echocardiography was performed, and left ventricular mass was calculated. As a measure of concordance, we computed correlation coefficients for left ventricular mass between first-degree relatives and between spouse pairs. After adjustment for center, gender, age, height, body weight, systolic blood pressure, antihypertensive treatment, smoking, alcohol intake, and physical activity, the intrafamilial correlations for left ventricular mass were 0.06 (P=0.57) in 91 spouse-spouse pairs, 0.14 (P=0.002) in 500 parent-offspring pairs, and 0.32 (P<0.001) in 179 sib-sib pairs. Across the four parent-offspring relations, the intrafamilial correlations of left ventricular mass differed. The mother-son (n=140, r=0.27, P<0.001) and mother-daughter (n=161, r=0.28, P<0.001) correlations were significant, whereas the father-son (n=101, r=0.04, P=0.69) and father-daughter (n=98, r=-0.09, P=0.38) correlations were not different from zero. Overall, the mother-offspring correlation coefficient was significantly higher than the father-offspring correlation (r=0.28 versus r=-0.04; P=0.005). Thus, maternal factors appear to have more impact on left ventricular mass of offspring than do paternal influences. Further studies are required to elucidate the genetic, epigenetic, and ecogenetic mechanisms underlying these divergent parent-offspring correlations.