ABSTRACTDuring a 14-month period of using matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS) for group B streptococcus (GBS) identification, we recovered 32 (1%) Streptococcuspseudoporcinusisolates from 3,276 GBS screening cultures from female genital sources (25 isolates from pregnant women and 7 from nonpregnant women). An additional two S. pseudoporcinusisolates were identified from a urine culture and a posthysterectomy wound culture. These isolates were found to cross-react with three different GBS antigen agglutination kits, PathoDx (Remel) (93%), Prolex (Pro-Lab Diagnostics) (38%), and Streptex (Remel) (53%). New approaches to bacterial identification in routine clinical microbiology laboratories may affect the prevalence of S. pseudoporcinus.