The nutritional quality of the host plant is one of the most important factors of growth and reproduction for crop pests. In order to investigate the impact of nitrogen on the biology and demography of Tetranychus urticae Koch (Acari: Tetranychidae), cucumber plants were nourished by four levels of nitrogen: N1 (10 meq /L NO3-), N2 (12 meq/L NO3-), N3 (15 meq/L NO3-) and N4 (20 meq /L NO3-). The experiments were performed under laboratory conditions at 25+/-1 °C, 60+/-5 % RH and a photoperiod of 16:8 (L:D) hours. Based on the results, increasing nitrogen nutriment was associated with a diminution of pre-imaginal duration in female mites from 13.13 to 10.74 days. In the opposite direction, the population reared on nitrogen-deficient cucumbers exhibited the highest rates of net fecundity (36.79 eggs/female) and net fertility (27.22 eggs/female). However, no considerable variation was demonstrated in fertility life-table parameters. The greatest net reproductive rate (R0) was observed when using the deficient (N1) nitrogen solution (22.12 females/female/generation). Additionally, the intrinsic rate of natural increase (rm) was estimated to be 0.178, 0.171, 0.183 and 0.185 females/female/day on cucumbers which were nourished by 10 to 20 meq/L NO3-, respectively. Finally, the mean population doubling time (DT) ranged from 3.72 to 4.04 days, and was at a minimum with the excess (N4) nitrogen solution and at a maximum with the moderately deficient (N2) treatment