Callus and suspension cultures of Mirabilis jalapa (four o’clock flower or Marvel of Peru) were induced from leaf explants using Murashige-Skoog medium. Callus, suspension and immobilised cell cultures of the plant synthesised both extracellular and intracellular protease. When compared with the leaves of the original plant, the proteolytic enzyme activity was 54- and 36-fold higher in the cell suspension and the callus cultures, respectively. Some of the sucrose was converted to glucose and fructose by the cultures and all three sugars were consumed simultaneously. Suspension and immobilised cultures also produced ethanol during batch cultivation. Investigation of the kinetics of protease production indicated that protease was produced with a rate proportional to the growth rate.