Crystalline cell surface layers (S-layer) of the bacteria species Deinococcus Radiodurans are used as an anometric template for patterning thin ferromagnetic films. A hexagonal pattern of uniform 10-nm-wide dots and a lattice,constant of 18 nm is fabricated from 2.5-nm-thick sputter deposited Co, FeCo, Fe, CoNi, and NiFe. Suitable parameters for the subsequent Ar ion etching are elaborated. For successful patterning, the etching energy ranges from 50 to 300 eV and the etching time from 17 to 283 s at an ion current of 1.5- 5.5 muA/cm(2). The formation of nanodot arrays is demonstrated by scanning electron and scanning force microscopy.