Magnetization measurements using a Gd5(Si1.95Ge2.05) single crystal with the magnetic field applied along three crystallographic directions, ,  and , were carried out as a function of the applied field (0–56 kOe) at various temperatures (∼5–320 K). The magnetic field (H)–temperature (T) phase diagrams were constructed for the Gd5(Si1.95Ge2.05) single crystal with field along the three directions. A small anisotropy was observed. The magnetocaloric effect was calculated from isothermal magnetization data, and the observed anisotropy correlates with the H–T phase diagrams. The results are discussed in connection with the magnetic field induced martensitic-like structural transition observed in Gd5(Si2Ge2)-type compounds. © 2003 American Institute of Physics.