Agrobacterium is the largest method employed to transform woody plants. The bacterium is required to introduce the transgene into the plant nuclear genome. After transferring T-DNA to the plant cell, the bacteria affect plant growth negatively and have to be eliminated from plant tissue culture medium through the use of antibiotics. The effect of different antibiotics (timentin, cefotaxime and carbenicillin) on in vitro shoot regeneration of teak (Tectona grandis L. f.) was compared in hypocotyl, mature cotyledon and cotyledonary segments explants. Timentin and cefotaxime (100-300 mg l-1) did not affect shoot regeneration and the number of shoots per explant. Moreover, at these concentrations, the two antibiotics seem to stimulate shoot regeneration. Carbenicillin at a dosage of 300 mg l-1 as well as cefotaxime and timentin at a dosage of 500 mg l-1 induced abundant calli formation and inhibited regeneration. Our data show that cefotaxime and timentin (300 mg l-1) can be harmless to teak regeneration and can be used as bactericide agents during Agrobacterium-mediated transformation of Tectona grandis. Furthermore, we discuss the effect of antibiotic degradation on plant morphogenesis and its effect on regeneration from different explants.