The effects of explant types and plant growth regulators on callus induction, callus proliferation, and plant regeneration in caladium were investigated, with the aim to develop an efficient procedure for producing friable callus with sustained regeneration potential. Callus was successfully induced from fully expanded leaves, young unexpanded leaves and petioles from greenhouse-grown plants, and tissue culture-derived leaves on all six media used. In vitro cultured leaves were found to be the optimum source of explants for callus induction, yielding 100% callus induction regardless of the medium used. Murashige and Skoog (MS) medium supplemented with 1 mg l^-1 thidiazuron (TDZ) and 1 mg l^-1 α-naphthalene acetic acid (NAA) showed the best response for callus induction. The induced calluses exhibited a compact appearance, grew slowly, but regenerated adventitious shoots or roots. The texture of calluses was further improved on MS medium containing 2 mg l^-1 TDZ and 2 mg l^-1 NAA, and calluses were capable of plant regeneration after 2 years of subculture. The results indicate that TDZ has a highly positive effect on organogenic callus induction and proliferation in caladium.