Fluorescence efficiencies for excitation of nitrogen by 1-5-MeV positive ions have been measured at pressures of 2-19 torr. Typically, N2 pressure of 3.6 torr was required to stop a beam of 4-MeV Ne+ in the 1.5-m-long collision chamber. Power output in the 3914-A (0,0) N2+ first negative band was measured with a photometer, and low-pressure efficiencies were calculated from the collisional deactivation rate. For Ne+, 0+, N+, N 2+, and O2+ ions with various initial velocities from 3.1 to S.3X lOS cm/sec, the low-pressure efficiencies were between 0.4% and 0.6%. 3914-A efficiencies were, for 2.0 and 3.4X10 8 cm/sec Kr+, 0.27% and 0.35%, and for 1.3SX10 9 cm/sec H+, 0.67%. Spectra of the nitrogen emission in the 3400-7800-A range were recorded. N2+ first negative and N2 first and second positive bands were prominent, with most first negative in the v/=O vibrational sequence, and most second positive in the v'=0-2 sequences. The spectra were corrected for collisional quenching and low-pressure efficiencies were determined relative to the 3914-A band. For 4-5-MeV, N+, Ne+, N 2 +, and Kr+, total efficiencies for the second positive v'=0-2 sequences were about 1.5 times the 3914-A efficiencies. Efficiencies were determined for 10 first positive bands of the v'=2 to 7 sequences excited by 4.7S-MeV Ne+; the (2,0) and (3, 1) band efficiencies, for example, were about one-fourth the 3914-A efficiency of 0.52%. The nitrogen fluorescence excited by the ions has a spectral intensity distribution similar to those observed by Hartman for SSO-eV electrons in air and by Mitchell for J .S-keV x rays in N2•