Three-photon absorption (3PA) of two stilbazolium-like dyes containing conjugated triple bridge (abbreviated as APAI and PPAI) has been determined by using a Q-switched Nd:YAG laser pumped with 35 ps pulses at 1064 nm in DMSO. Nonlinear absorption coefficients alpha(3) derived from 3PA fitting curves are 4.3 and 3.2 x 10(-21) cm(3)/W-2, respectively. Large optical power limiting induced by 3PA has also been demonstrated for both dyes. When the maximum incident irradiance reaches to 400 GW/cm(2), the limiting nonlinear transmissions T-lim can reach to 13 and 17% with maximum transmitted radiances of 17 and 44 GW/cm(2), respectively. (C) 2003 Elsevier Science B.V. All rights reserved.