We synthesized two-photon absorption probes based on naphthalene and anthracene: 1,1'-dimethyl-4,4'-(2,6-naphthylenedi-2,1-ethenediyl)dipyridinium diiodide (NP) and 1,1'-dimethyl-4,4'-(2,6-anthrylenedi-2,1-ethenediyl)dipyridinium diiodide (AC). These two probes were successfully accumulated in mitochondria with different fluorescence colors: yellow (NP) and red (AC). Two-photon absorption cross sections (a(2)) were 712 and 685 GM (1 GM = 10(-50) cm(4) s photon(-1) molecule(-1)), respectively. These values are nine times larger than the sigma((2)) of the commercially available mitochondria-selective probe with efficient two-photon absorption property (rhodamine 123).