Growth and caffeine production of callus cultures derived from stem segments of the coffee plant (Coffea arabica) were studied. Primary as well as subcultures grow – in terms of dry weight – exponentially with a duplication time of 12 to 13 days. The formation of caffeine is parallel with the increase of callus dry weight, reflecting a fairly constant production per unit dry weight. The theoretical percentage of caffeine in the cultures amounts to 1.0–1.6 %. When the tissue caffeine concentration exceeds the limit of 900–1000 μg/ml tissue, both callus growth and caffeine formation are inhibited to the same extent. It is suggested that caffeine synthesis is closely connected with the growth processes.