The aggregation behavior of the phenylhydrazone dye [(4-octadecyloxy)benzaldehyde]-4’-nitrophenyl-hydrazone (PD) and hemicyanine dye (E)-N-docosyl-4-[2-(4-diethylamino)phenyl)ethenyl]pyridinium bromide (DAEP), in Z-type Langmuir-Blodgett (LB) multilayers has been studied by absorption, steady state and time-resolved fluorescence spectroscopies. The LB multilayers of pure PD and DAEP showed J- and H-aggregate formations, characterized by a large red shift (Delta E similar to 2398 cm(-1)) and blue shift (Delta E similar to 1898 cm(-1)), respectively. The main fluorescence emission bands were found at 560 and 584 nm for PD and DAEP multilayers. The fluorescence decay profiles of PD and DAEP in LB films could be best fit by using a biexponential decay model. Our results revealed that there mainly existed two species (monomer and dimer) in the LB multilayers with characteristic fluorescence decay time in the order of ns and 10 ps, respectively.