The band structure as well as electrical and optical properties of Hgl-xMnxTe are remarkably similar to those of Hg l-xCdxTe, making Hgl-xMnxTe a competitive candidate for applications in infrared detectors. In this paper we examine the properties of Hg1-xMnxTe which are relevant to this application. Hgl-xMnxTe is formed by substitution of tie magnetic Mn ions for Hg in the HgTe lattice; although Mn is not a group II element, Hgl-xMnxTe crystallizes in the zincblende structure, forming good quality crystals up to x 0.3S. Its energy gap and related band parameters vary with x, but at a rate about twice as fast as in Hgl-xCdxTe. The electrical properties of Hg1-xMnxTe are again similar to those of Hgl-xCdxTe, including electronic mobilities and doping characteristics. As-grown Hgl-x MnxTe is p-type due to a natural tendency to form Hg-vacancies, which act as acceptors and whose concentration can be reduced by appropriate annealing. Because Mn is a magnetic ion, Hg l- differs from Hgl-xCdxTe in its magnetic properties, as well as in the behavior of its electrical and optical properties in the presence of a magnetic field. For example, for x > 0.17 Hg1-xMnxTe exhibits a transition to the spin glass phase at low temperatures. Furthermore, the presence of Mn ions leads to an exchange interaction between the localized magnetic moments and the band electrons, which in turn affects the band parameters and leads to new and spectacular effects in the transport and optical properties. It is to be emphasized that magnetic properties associated with the Mn ions, such as electron paramagnetic resonance, magnetic susceptibility, etc., also offer a unique handle by which the distribution of Mn over the lattice (e.g., its tendency to form clusters) can be studied.