Data on 772 lambs of elite a selection line and tester gronp born to 63 sires of Marwari breed were scrutinised to assess the influence of various factors on birth, 3, 6, 9, 12 months weight and greasy fleece weight at 6 and 12 months (GFWI & GFWII) and selection index value (SIV). The overall least squares means were 2.80±0.01, 11.72±0.07, 15.22±0.05, 18.52±0.06, 20.97±0.09, 0.51±0.005, 0.59±0.007 kg and 4.157±0.033, respectively. Sex and year showed significant effect on all the traits except the effect of sex on greasy fleece weight in first clip and effect of year on birth weight. The effect of genetic group showed highly significant influence on GFWII and SIV. Regression of dam's weight at lambing and birth weight on 3 months weight was highly significant and regression of previous weights at later weights were also significant. The regression of 6 and 12 months weights at first and second fleece clip was significant. The heritability estimates were 0.043±0.032, 0.125±0.042, 0.258±0.054, 0.20l±0.049, 0.169±0.047, 0.515±0.058, 0.036±0.031 and 0.418±0.059 respectively for the traits under study. All genetic and phenotypic correlations were positive and low to medium in magnitude.