Friable calli, obtained from Tropaeolum majus leaves, on Gamborg B5 medium supplemented with 2,4-D, kinetin and casein amino acids, were used for the establishment of cell suspension cultures in the same liquid medium. Different basal media, inoculum densities, sucrose concentrations, nitrogen sources and cysteine levels were assayed for biomass production. The best growth rates were achieved in Gamborg B5 medium supplemented with 1.5 mg litre-1 2,4-dichlorophenoxyacetic acid, 0.1 mg litre-1 kinetin, 2 g litre-1 casein amino acids, 100 mg litre-1 cysteine and with an initial inoculum of 50 g (fresh weight) litre-1. The doubling time obtained under these conditions was about 55 h.