Bioassay-directed fractionation of ethanolic extracts of the roots of Erythrina mildbraedii, a plant used in the indigenous system of medicine in Nigeria, resulted in the isolation of the previously known pterocarpans erythrabyssin-II and isoneorautenol and the new pterocarpans erybraedins A, B, and C. The structures of the new compounds were determined by chemical transformations and/or spectroscopy and their in vitro antimicrobial spectra and potencies are reported.