Studies were performed on the alkaloid content of leaf and stem callus cultures of CINCHONA PUBESCENS Vahl with respect to the influence of plant growth regulators and light. The same alkaloids were found in the analysed tissues - with some quantitative differences. In general, a medium containing zeatin: 1 microM and 2,4-dichlorophenoxyacetic acid: 1 microM gave a higher alkaloid production than a medium containing benzyladenine: 8.1 microM and 2,4-dichlorophentoxy acetic acid: 4.5 microM. The alkaloid production in the unorganized callus cultures was stimulated by light. Anthraquinones were found in all tissue cultures.