A pots experiment was conducted in the greenhouse of the Department of Biology, College of Education for Pure Sciences Ibn Al-Haitham, University of Baghdad, for the growing season 2022-2023 to find out the effect of the concentrations of the growth regulator brassinolide on some morphological characteristics, the concentrations of macroelements (nitrogen, potassium, phosphorus) and active compounds of the plant Eruca sativa Mill. The study was designed based on the Complete Randomized Design (CRD) and three replicates of 12 pots each, so that the number of pots was 36. Four concentrations of the growth regulator brassinolide (0, 1.5, 2.5, and 3.5) mg L^-1 were used. The results showed that spraying with the brassinolide growth regulator increased all the average characteristics studied, such as plant height, total chlorophyll index by Soil Plant Analysis Development (SPAD) in the leaves, nitrogen concentration and potassium concentration, especially at a concentration of 2.5 mg L^-1, while it had no significant effect on phosphorus concentration. The results also displayed a significant effect in all active compounds of the plant, especially at a concentration of 2.5 mg L^-1, while the results of the examination and chromatographic diagnosis using High Performance Liquid Chromatography technique gave the diagnosis of nine active compounds in the E.sativa plant, namely: Progoitrin, Glucoalyssin, Gluconapin, 4-OH-Glucobrassicin, Glucoerucin, Glucobrassicin, Methoxybrassicin, Gluconasturtin and Neoglucobrassicin.