The Atlas provides digital spectra to assist the classification of OB spectra for 78 standard objects in the wavelength range 395.0-475.0 nm. Spectral types range from O3 - B3 (-B8 at Ia). The Atlas provides contemporary digital data comparable to the earlier printed Atlasses by Morgan et al. (1943), Abt et al. (1968), Yamashita et al. (1977) and Morgan et al. (1978). The digital data were obtained with the Shectman/Heathcote two- dimensional, photon-counting detector on the Casegrain spectrograph at the CTIO 1-meter telescope during October 1988 and March 1989. The 3-pixel resolution is 1.5 Angstroem, and the full wavelength coverage is 3800-5000 A. The data were extracted and rectified by using a uniform template followed by a low-order spine fit.