The primary objective for many oil palm growers has been to enhance crop yield, which can be achieved through the cultivation of more productive varieties. Therefore, there is a need to study new planting materials to find the optimum planting density in oil palm plantations. Oil palm growth and yield performance of two planting materials (PS1 and DxP) were determined using four planting densities and three nitrogen fertiliser rates. The analysis of variance for fresh fruit bunch (FFB) and its components over seventeen years of recording show no significant interaction between planting density, progeny lineage and nitrogen (N). The N had a significant effect on FFB yield where N1 rate was a significant difference in average FFB yield by 0.89 t ha^-1 as compared to the control. However, a higher rate of N (N2) did not significantly increase FFB yield since the difference is only 0.09 t ha^–1. The standard rate of N fertiliser significantly produces maximum cumulative yields over seventeen years of harvesting. Vegetative growth shows that higher planting density increased rachis length, frond length, height, leaf area and leaf area index. PS1 exhibited a significantly shorter rachis length measuring 3.08% less at 6.18 m, in comparison to DxP which measured 6.33 m. Over 17 years of harvesting, a planting density of 140 palms ha^–1 yielded the highest cumulative and average FFB yield amounting to 426.96 and 24.19 t ha^-1 yr^-1 respectively. However, it was not significantly different to the yield achieved at a density of 160 palms ha^-1, which yielded cumulatively at 425.68 t ha^-1 yr^-1 and average of 24.12 t ha^-1 yr^-1. The study shows that the standard practice of 140 palms ha^-1 continues to be the preferred agronomic optimum planting density.