Pseudomembranous enterocolitis (PMEC) was first documented in 1893. Since this initial description, confusion has reigned in the medical literature concerning its nature and differentiation from such entities as necrotizing enterocolitis and staphylococcal enterocolitis. Since the 1950s, volumes have been written on PMEC and its association with a multitude of different antibiotics. PMEC has generally been used as somewhat of a "wastebasket" designation, being applied to any postoperative patient who develops significant diarrhea while on broad-spectrum antibiotics. More recently, a resurgence of interest in PMEC has led to its recognition as a specific disease entity and to a greater understanding of its etiology. The current review traces the history of PMEC, distinguishes if from similar disease processes, and describes its clinical presentation, diagnosis, and management. PMEC is particularly distinguished from antibiotic-associated diarrhea and certain forms of antibiotic-associated colitis.