Fluorescence recovery after photobleaching (FRAP) is one of the most powerful and used techniques to Study diffusion processes of macromolecules in membranes or ill bulk. Here, We study the diffusion of alpha-chyrnotrypsin in different crowded (Dextran ill Vitro Solutions using a confocal laser scanning microscope. In the considered experimental conditions, confocal FRAP images Could he analyzed applying, the Uniform circular disk approximation described for a nonscanning microscope generalized to take into account anomalous diffusion. Considering, the slow diffusion of mancromolecules in crowded media. we compare the fitting of confocal FRAP Curves analyzed with the equations provided by the Gaussian and the uniform Circular disk profile models for nonscanning, microscopes. As the fitted parameter variation with the size and concentration of crowders is qualitatively similar for both models, the use of the uniform circular disk or the Gaussian model is justified for these experiments. Moreover, in our experimental conditions, alpha-Chymotrypsin shows anomalous diffusion (alpha < 1). depending oil the size and concentration Of Dextran molecules, Until a high concentration and high size of crowding, went are achieved. This result indicates a range of validity of the idealized filling expressions used, beyond which Other physical phenomena Must be considered.