Enterococcus casseliflavus is a yellow-pigmented, motile, Gram-positive coccus that is only rarely isolated from clinical specimens. We report the first case of neonatal sepsis due to E. casseliflavus in a premature neonate. Precise identification of Enterococcus species is difficult but is of significant clinical interest because of the intrinsic low-level resistance to vancomycin of species such as E. casseliflavus and E. gallinarum.