The heritability and heterosis were estimated in the 1982-1993 hand pollination programme of the Rubber Research Institute of Vietnam. The estimates were based on young seedlings and clones at 28 months old and hybrid clones after 6 years of tapping. In general, heritability was high for yield, growth and bark thickness. The coefficient of broad sense heritability varied from 0.31 to 0.93, from 0.31 to 0.69 and from 0.22 to 0.79 for yield, girth and bark thickness, respectively. In the juvenile period, the yield of RRIVs hybrids had much higher heterosis and genetic and phenotypic variabilities than other traits. The best heterosis for yield was 252.7;over the parents. Girth exhibited lower heterosis with highest levels of only 34;over the parents. This indicates that selection for high yielding genotypes could be easier than for growth in the 1982-93 progenies. The elite hybrid (LH 90/1125) could be 259;and 20;over the PB 235 control clone for yield and growth, respectively, in young period. High heterosis and performance of elite hybrids derived from Amazonian materials suggests that although materials from this source are low in yield, they could be improved for further utilization in the longterm breeding programme. The high correlation coefficient between yield and growth (0.285 - 0.659) permits the choice of hybrids combinig advanced economic characters from the 1982-93 progenies. The correlation coefficients between the juvenile period and the mature period for the 1982-83 progenies were 0.57, 0.53 and 0.48 for girth, yield and bark thickness, respectively. This implies that the nursery performance of the offspring of clones could be reliably used for early estimation of genetic parameters and identification of potential parents.