We have studied the effect of metal thickness for the metal-induced lateral crystallization (MILC) of a-Si on the off-state currents of poly-Si thin-film transistors (TFTs). It is found that they decrease with decreasing the Ni thickness for MILC. The Ni-MILC poly-Si TFT with the Ni area density of 1.4x10(14) cm(-2) exhibited a field-effect mobility of 53.5 cm(2)/Vs and minimum leakage current of 0.44 pA/mu m at V-ds=-10 V. However, the off-state current is 6.6 pA/mu m when the Ni density is 9.2x10(15) cm(-2), corresponding to the average Ni thickness of 10 A. It is concluded that the average Ni thickness for MILC should be less than 0.79 A to have low off-state currents from our experimental data.