The CaMn 2 - x Fe x Ge 2 (ThCr 2 Si 2 -type structure) solid solution was studied by means of X-ray powder diffraction, magnetic measurements and neutron diffraction experiments. The magnetic structures of the CaMn 1 . 3 Fe 0 . 7 Ge 2 , CaMnFeGe 2 and CaMn 0 . 8 Fe 1 . 2 Ge 2 compounds have been determined between 2 and 500 K. Below T C (~190 K), the CaMn 0 . 8 Fe 1 . 2 Ge 2 compound exhibits the collinear ferromagnetic structure, denoted F, only encountered up to now in the UMn 2 Ge 2 compound. The results lead to the construction of a partial x-T magnetic phase diagram. Results are compared and discussed with those observed in the isotypic LaMn 2 - x Fe x Ge 2 and NdMn 2 - x Fe x Ge 2 solid solutions.