This study aimed to determine the effects of polyethylene glycol (PEG) as an abiotic elicitor and nutritional factors (different ammonium/nitrate ratios, carbon source and amount) in the culture medium on the production of Caffeic Acid Derivatives (CADs) in callus cultures of Echinacea purpurea L. Petiole and root explants were cultured on MS medium modified in terms of different types (sucrose and maltose) and amounts (sucrose 15, 45, 60 g l-1, and maltose 15, 30, 45, 60 g l-1) of carbon source, different concentrations (5, 10, 15 g l-1) of PEG and ammonium nitrate ratios (0:35, 5:25, 15:15, 35:0 mM). The amounts of CADs in the callus obtained at the end of the 10-week culture period were analysed. In both explant types, the highest amount of CADs were obtained from the medium containing 15 g l-1 sucrose and 15 or 30 g l-1 maltose applications, while the highest amount of CADs was obtained in the medium containing 0:35 mM ammonium/nitrate in nitrogen applications. While the highest amount of CADs in root explant was obtained from the medium containing 10 g l-1 PEG applications, CADs content could not be obtained in petiole explant. As a result, the highest amounts of caftaric, chlorogenic, caffeic, and chicoric acids (respectively, 9.38, 0.71, 0.29, and 34.77 mg g-1) were determined at callus obtained from root explant cultured on MS medium containing 30 g l-1 sucrose and 0:35 mM ammonium/nitrate. In conclusion, optimization of culture conditions and different elicitor applications were made to increase secondary metabolite content in E. purpurea L. under in vitro conditions and the results obtained were presented comparatively.