The Humic substance has been recognized widely as a plant growth promoter because they induce changes in root, architecture and dynamics of growth which result in larger root size. The aim of this study was evaluating the effect Humic acids on the chili pepper (Capsicum annuum) and eggplant (Solanum melongena) plants growing in soils fertilized with urea. 200 g of soil were incorporated to the fertilizer once and the Humic acid in concentrations of 0.05%, 0.1% and 0.2%. All measurements growths were carried out during 45 days growth. The finding shows that all treatments cause significant increases (p < 0.05) in the total area of roots. For the chili pepper, the multiple comparison tests of Tukey and Dunnett showed that there was a statistically significant difference between the control soils and the soils containing 0.1% and 0.2% of Humic acid. By the opposite, no statistical differences (p > 0.05) were observed among control soil and those containing 0.05 % of Humic acid. Concerning the eggplant, significant differences were established (p<0.05) between the control and samples incorporated with 0.1% and 0.2% of Humic acid. The Humic acids act as a growth biostimulant in chili pepper plants (Capsicum annuum) and eggplant (Solanum melongena).