The comparative numerical studies of polarized fluorescence decays for membrane vesicles suspension and macroscopically ordered planar membranes or Langmuir-Blodgett films, are presented. Angular alignment and rotational dynamics of fluorophores is analyzed by means of two very different optimization methods, namely: (a) a gradient-expansion (GE) method and (b) a method based on genetic algorithm (GA). The GE method requires the initial values of the fitted parameters, while in the GA approach only physically allowed lower and upper bounds for the values of the fitted parameters have to be predefined. © 2005 Elsevier B.V. All rights reserved.