Photoluminescence (PL) spectra of CdTe single crystals and films, undoped and Ag-doped, were studied in the range of the photon energy (hν): 1.5-1.6 eV, at 10 K. Films were doped during the growth process. Thin layers of Ag were vacuum evaporated onto the surface of undoped CdTe crystals, then were submitted to thermal annealing in a N[SUB2] + 2% H[SUB2] ambient at 400 °C for 3 h. PL spectra of crystals exhibit a donor-acceptor pair (DAP) emission at hn51.491 eV named here DAP[SUP2,SUBAg]) with the highest intensity with respect to other signals. The PL of films is characterized by a peak at 1.5 eV followed by several phonon replicas. In both cases, the DAP emissions are due to the Ag-impurity presence and are accompanied by phonon replicas. Unannealed intrinsic crystals exhibit a unique broad DAP[SUP1,SUBAg] peak at hn = 1.501 eV, and one month aged at room temperature Ag-doped crystals only display a wide DAP[SUP2,SUBAg] peak at hn = 1.491 eV with 65% of its initial intensity, that reflects a reduced density of Ag diffused-doping levels. The origin of DAP lines in a PL spectra of CdTe:Ag has not been completely well defined until now, and we have introduced some explanatory conclusions about and a simple model for electronic transitions. This issue is important because Ag is an everpresent residual impurity in CdTe. [ABSTRACT FROM AUTHOR]