Slope stability analysis is one of the oldest fields of geotechnical engineering and it has been performed for many decades, but it is still an active research topic, both in academia and in practice. Geotechnical engineers frequently use back analysis of old and new slides to estimate the shear strength of soils involved in construction of retaining structures and slope reinforcing or redesigning projects. Nowadays various software based on the two-dimensional (2D) method of Slices are used on a routine basis to perform such type of analysis. Little or no attention is given to the three-dimensional (3D) features of the problem, usually because the 3D analysis is more time consuming, because 3D methods and software are not so widespread and proven as 2D ones and because the 2D factor of safety is perceived to be lower than the 3D factor of safety, thus conservative. However, that may not always be the case. In this paper, an active slide is analyzed by a 2D method of Slices and by two quasi-3D methods. The slide took place in tropical soils. The factors of safety obtained by each method are compared, showing a small difference amongst them.