While CdGeAs2 single crystals are promising for infrared second harmonic generation, it has been difficult to reproducibly grow low loss optical material, particularly in the 5 mum region. In addition, a correlation between processing conditions and absorption has eluded various researchers studying this problem. This paper describes a series of etching experiments which were undertaken to see if there might be a relationship between dislocation density and optical absorption. In this study single crystals were grown from stoichiometric melts along the common [001] direction by the horizontal gradient freeze method. Etch pit densities (EPD) of > 10(6) cm(-2) were observed at the edges of the boules, while almost no etch pits were found at the center. Infrared transmission images indicated that the higher EPD regions had lower optical absorption. It was also found that the absorption coefficients (a) varied from 2.1 to 18.2 cm(-1) along the boule axis. Moreover, the etch pits, which formed near the edge of the crystal adjacent to the crucible walls, were created by slip along the {1 1 2} planes, which make up the growth interface. These results suggested that in order to obtain a more uniform absorption within each boule, dislocation formation should be minimized. Our first approach involved changing the orientation of the growing crystal to the [1 12] direction. The results of these experiments were very encouraging, showing that a considerably improved radial and axial absorption uniformity was achieved, as well as the lowest optical losses measured (minimum alpha = 0.18 cm(-1)) compared with similar samples grown along the [00 1]. It can be concluded from this study, therefore, that the growth orientation plays an important role in the absorption behavior of CdGeAs2. (C) 2004 Elsevier B.V. All rights reserved.