TALREN 4 slope stability program allows checking of the stability of geotechnical structures, with or without reinforcement. The main features include: drawing the problem geometry with the mouse, handling of construction stages and calculation conditions in a single project file, automatic searching for the critical failure surface, capability to load a background gif or jpg picture, links with Plaxis v8 (reading of geometry and pore pressures), wizards (partial safety factors, unit skin friction). It uses an improved version of the Talren 97 calculation kernel with no limit on the number of elements. It uses classical moment equilibrium (Bishop or Fellenius) or global (force and moment) equilibrium methods to evaluate the stability along circular or non-circular failure surfaces. It also includes yield design calculation methods (with logarithmic spirals failure surfaces), thus enabling new applications for the program (gabions stability, earth pressures calculations, additional slide mechanisms, etc). The slope stability can be determined by a traditional analysis (global safety factor) or by an Ultimate State Analysis considering partial safety factors defined by the user. Handles complex slope and soil geometries, as well as distributed loads, line loads (inclined or vertical), and applied moments. Pore pressures may be defined as: nodes of a triangular mesh; at each point defining a non-circular failure surface; or as hydrostatic pressure resulting from external water tables. Reinforcement types modelled: soil nails, ground anchors, reinforcing strips (Reinforced Earth, Paraweb) or fabrics (geotextiles), piles and braces. Reinforcement properties: tensile or compressive strength, bending moment, or any combination thereof. It has a multi-criterion option for nails (calculated traction+shear). The code can also take into account seismic loadings, non-linear shear strength curves and anisotropic cohesion. It is available in both English and French. A demo version is available on the www.