Characteristics of a Fe:ZnSe laser are studied at room temperature. The laser active elements are heavily doped single crystals with the $$\hbox {Fe}^{2+}$$ Fe2+ ion concentration $$n=0.64\times 10^{19}-5.7\times 10^{19}\hbox {cm}^{-3}$$ n=0.64×1019-5.7×1019cm-3 , grown from melt by the Bridgman method. The generated energy of 870 mJ is obtained at the total efficiencies with respect to the absorbed and incident energies $$\eta _{\mathrm{{abs}}}=43\%$$ ηabs=43% and $$\eta _{\mathrm{{inc}}}\approx 35\%$$ ηinc≈35% , respectively. The laser slope efficiency with respect to the absorbed energy is $$\eta _\mathrm{{slope}}\approx 50\%$$ ηslope≈50% . In a heavily doped active element with the $$\hbox {Fe}^{2+}$$ Fe2+ concentration $$n=5.7\times 10^{19}\hbox {cm}^{-3}$$ n=5.7×1019cm-3 , in which the medium excitation depth is just a part of the total element dimension along the optical axis (the element is completely non-transparent for the pumping radiation), the radiation spectrum of the Fe:ZnSe laser shifts to the long-wavelength range by more than 300 nm as compared to spectra of the laser on crystals excited along the whole element length. It is shown that Fe:ZnSe lasers on heavily doped single-crystal elements can be efficiently excited by a radiation of a Cr:ZnSe laser without tuning the spectrum of the latter to the longer wavelength range.