A parametric study has been undertaken to determine the gain characteristics of flowing CO2-N2-He lasers employing a transverse-discharge configuration. Unlike conventional cylindrical discharge tubes, in this device the gas-flow and electrical-discharge paths lie perpendicular to the optical axis. Box lasers with various aspect ratios and electrode configurations were evaluated. The gain exhibited an inverse dependence upon the height of the box laser. The axial gain in the Faraday dark space is lower than in the region of the positive column, decreasing monotonically to zero at the cathode. The character of the axial gain profile is significantly changed by a reversal in the direction of gas flow relative to the polarity of the discharge. For a volumetric gas flow of 0.3 scfm, a peak gain of 3.4 dB/m was attained with a box laser characterized by 1/2-inch height, an 8:1 aspect ratio, and a 1-inch adjacent electrode spacing. Power output data are presented for a box laser employing a folded optical resonator.