Fe-doped 0.62Pb(Mg1/3Nb2/3)O-3-0.38PbTiO(3) (PMN-0.38PT) single crystals were grown by a modified Bridgman technique. Two kinds of single crystals with different iron ion molar ratios, (i) 0.2 mol% and (ii) 1.0 mol%, were obtained. The effect of doping iron ions on the dielectric and pyroelectric properties of the < 111 >-oriented PMN-0.38PT single crystals was examined. The temperature of the permittivity maximum (T-m) exhibits no dispersion behavior and decreases with increasing doping concentration. The dielectric loss of the 0.2 mol% Fe-doped PMN-0.38PT single crystal is much lower than that of the high dopant content crystal (1.0 mol%) and undoped crystal, which makes it possess excellent pyroelectric performance. By a dynamic method, the measured pyroelectric coefficient and detectivity figure of merit (F-D) of 0.2 mol% Fe-doped PMN-0.38PT single crystal are 439 mu C/m(2.)K and 56.3 mu Pa-1/2, respectively, both better than those of widely used pyroelectric single crystal LiTaO3. The results imply that the single crystal is a promising candidate for infrared detectors and other pyroelectric applications. The mechanism of doping effect was also discussed based on the principles of crystal chemistry.