A photoelectric UBV sequence in a low extinction Puppis field UBV photoelectric photometry, MK-dispersion slit spectra, and spectralclassifications based on objective prism spectra are presented for asequence of 116 early type stars in the Puppis region. The interstellarextinction, based largely on spectroscopic parallaxes, is found to beremarkably low for a field in the Galactic Plane, amounting to 0.30 mfor E(B-V) at r of about 6.3 kpc.