This paper deals with the spatial characterization of urban expansion by using spatial fractal analysis applied to multidate Multispectral Scanner (MSS) and Thematic Mapper (TM) satellite imagery. The investigation was focused on one small southern Italy town, for which the border was extracted from NASA Landsat images acquired in 1976 (MSS), in 1987 and 1998 (TM). The border was analysed using the box counting method, which is a well-know technique to estimate the spatial fractal dimension, that quantifies the shape irregularity of an object. The obtained results show that the fractal dimension of the border of the investigated town increases from 1976 to 1998, indicating a tendency toward a more irregular shape. This increase is also connected with the urban expansion and the population growth.