We measured the three-photon absorption spectra of two europium acetylacetonate-type complexes. The three-photon absorption peak wavelengths of tris(hexafluoroacetylacetonato)-europium(III) (Eu(hfa)) and tris(2-naphthoyltrifluoroacetonato)-europium(IE) (Eu(ntfa)) were 925 and 1025 nm, respectively. The peak values of the 3PA cross-sections of Eu(hfa) and Eu(ntfa) were 1.9 and 13.9 GM (1 GM = 10(-82) cm(6) s(2)), respectively. Using Eu(ntfa) as a probe, a three-photon microscope image of a living cell was obtained using a 1030 nm operating femto-second fiber laser as the light-source. Thus, Eu(ntfa) is a fiber laser excitable luminescent probe useful for three-photon microscopy.