This study was carried out to determine the effects of 24-epibrassinolide (24-eBL) and methyl jasmonate (MeJA) on cell growth and accumulation of secondary metabolites in immobilized cells of Hyoscyamus niger. For this purpose, different combinations of 24-eBL (0.5, 1.0, and 2.0 mg l(-1)) and MeJA (1.0 mM) were applied to cells immobilized with calcium alginate. At the end of the 30-day applications, fresh and dry cell weights, cell growth index, tropane alkaloids (hyoscyamine and scopolamine), phenolic (gallic acid, catechin, chlorogenic acid, caffeic acid, epicatechin, vanillin, p-coumaric acid, o-coumaric acid, ferulic acid, rutin, cinnamic acid, rosmarinic acid, and quercetin), and total phenolic content were determined. According to the results, 2.0 mg l(-1) 24-eBL for cell growth, 0.5 mg l(-1) 24-eBL for scopolamine and hyoscyamine, and all 24-eBL combinations with 1.0 mM MeJA for phenolic compounds were selected as the most effective applications. In conclusion, it was determined that the application of 24-eBL and MeJA may be successfully used to increase the production of secondary metabolites in immobilized cell cultures of H. niger when used in appropriate concentrations and combinations.