17 N. Ali J. Bakht K. Naveed M. Liaquat S. A. Khan M. Saeed S. Ali I. Hussain S. M. Khan M. Salim Journal of Animal and Plant Sciences JAPS 20152015/06/01 25 3 321-326 1018-7081 NA Mid-parent and better-parent heterosis was estimated in Brassica juncea L. lines by using 8 x 8 full diallel. Randomized complete block design (RCBD) with two replications were used for 56 F hybrids and their parent. Out of 56 crosses, 34 1 crosses showed significant heterosis for oil %age. Significant positive heterobeltiosis was recorded in 26 crosses. For glucosinolate content out of 56 F s significant negative heterosis was monitored for 16 crosses. Significant negative 1 heterobeltiosis was observed in 7 crosses. In case of erucic acid, 32 crosses confined significantly negative heterosis. On the other hand 21 crosses exhibited significant negative heterobeltiosis. For protein, 32 crosses showed significant heterosis. Significant positive heterobeltiosis recorded for 27 crosses. In case of oleic acid content, 49 crosses revealed positive values, with significant positive heterosis in 17 crosses. Data for heterobeltiosis showed that positive values were recorded for 41 crosses. Significant positive heterobeltiosis was detected for 8 crosses. Data regarding linolenic acid demonstrated that out of 56 crosses, 32 crosses contained significantly negative heterosis. Heterobeltiosis values for linolenic acid content showed that, negative values were detected for 22 crosses. Significant negative heterobeltiosis was recorded for 11 crosses. Priyamedha et. al. 2014). Indian mustard seed contains Heterosis, Mid-parent, Better-parent, Mustard, Brassica juncea L, Fatty acids. Pakistan Agricultural Scientists Forum https://thejaps.org.pk/AbstractView.aspx?mid=2015-JAPS-650