Extensive proliferation via axiallary meristems can be induced in potato shoot-tips (15–20mm) cultured in liquid media. Proliferation is greatest when a 4-week period of shake culture for 1 1/2 h per day is followed by stationary culture. The rate of proliferation is influenced by light, temperature and phytohormones. Gibberellic acid and kinetin are essential, but the optimal concentrations are different for initial inocula and for subcultures. Under optimal conditions shoot multiplication rates in excess of 10–25 fold per 8 weeks are obtained, but there are genotypic differences in the response.