The spectrum emitted by neutral antimony atoms has been photographed, measured, and analy~ed. Measured wavelengths and estimated relative intensities are given for 466 lines, ranging from 1388.91 to 12466.75 A in wavelength and from 1 to 2500 in intensity. Nearly 80 percent of these lines are classified as combinations of 60 even energy levels arising from 582 5p2 n8, 582 5p2 nd, and 585 p' electron configurations and 31 odd le vels from 582 5 p3, 582 5p2 np, and possibly 582 5p2 nj. The average difference between observed and computed wave numbers is 0.15 cm-I . A paucit y of lines in the visible sp ectrum and intense radiation of antimony atoms in the ultraviolet and infrared are seen to be conseq uences of the relative values of various groups of levels. Although it is not possible to give a complete qua ntum interpretation of all the levels, several spectral series of t he type 582 5 p3_582 5p2 ns are proposed, and an absolute value of 69700 cm-I is deduced for the ground state, 582 5p3.'SO}i, of neutral antimony atoms. From spectroscopic data , t he principal ionization potential of antimony is calculated to be 8.64 volts.