A transverse framework for an avionics bay of an aircraft is delimited by a primary structure and a floor, the transverse framework having a mesh structure with square and/or rectangular mesh cells. According to one arrangement, an avionics bay of an aircraft includes two longitudinal rows of avionics racks, parallel to the longitudinal direction and arranged on each side of a clear zone, and a transverse avionics rack supported by the transverse framework situated to the rear of the two longitudinal rows of avionics racks at the rear boundary of the avionics bay. This transverse framework makes it possible to optimize the space occupied by the avionics bay.