Time course of the growth of cultured Pinellia ternata plants was investigated.Corm-like bodies were cultured in a MS liquid medium containing 0.25mg/l IAA and 0.5mg/l BA by shaking. On the 13th, 27th, 41th, and 54th day, the dry weight of each organ-corm-like body, leaf blade, petiole, root-was measured. From these data, growth parameters and distribution rate of dry matter in each organ were calculated.Relative growth rate was at its maximum at the beginning of culture and then decreased gradually. The growth rate in the dry matter of the whole plant was at its maximum between the 13th-27th day.The time course of the distribution rate of dry matter in each organ indicates that during the first half of the culture period, mainly leaf blades and petioles grow and during the latter half, mainly corm-like bodies grow.Judging from the weight of corm-like bodies obtained for a fixed period and the cost in gaining corm-like bodies, the best culture period was 41 days.