Time-resolved polarized fluorescence spectroscopy has for the first time, been applied to the study of chromophores in a macroscopically aligned lyotropic nematic phase. The phase is composed of potassium dodecanoate, potassium chloride and water and contains long rod-like aggregates, that are aligned with their long axes parallel to an applied magnetic field. Pyrene, 1-pyrene dodecanoic acid, 1-dodecylpyrene and l-palmitoyl-2-(6-pyrenylhexanoyl)-sn-glycero-3-phosphoryl-choline are solubilized in these aggregates. The photophysics of these probes is a single exponential and typically between 130 and 200 ns in non-degassed samples. For all the probes the plane of the pyrene molecule tends to be oriented perpendicular to the symmetry axis (C∞axis) of the aggregate. The order parameters describing the orientation of the electronic transition dipole moment relative to this axis are typicallyc.-0.05. It is concluded that the translational and the local rotational motions of the probes are fast compared to the fluorescence lifetimes. The correlation times characterizing these motions are shorter than 20 ns. Finally, no slow motions such as fluctuations of the normal to the surface of the rod-like aggregate or a slow wobbling of theC∞-axis can be detected duringc.1 μmls.