Ductile-to-brittle transition temperatures obtained from notched bar bend tests were used in conjunction with fracture surface analysis by scanning electron microscopy (SEM) to study various aspects of temper embrittlement in a series of 3.5Ni-1.7Cr-0.4C base steels. Addition of Mo was found to eliminate embrittlement due to step cooling for Sb, Sn, As, and Mn, but not for P. Mn as well as Si, Bi, Se, Ge, and Te are shown to be embrittling elements. The phenomenon of intergranular dimpled rupture was common in these steels. Steels exhibit intergranular embrittlement after quenching from austenite, to an extent determined by the quenching rate.