We studied 31 cases of postoperative pyogenic spondylodiskitis (POS), comparing them with 72 cases of nonpostoperative pyogenic spondylodiskitis (NPOS). POS represents 30.1% of cases of pyogenic spondylodiskitis. The onset of symptoms occurred an average (+/-SD) of 27.7 (+/- 25.3) days following surgery. Predisposing factors were less frequent in POS than NPOS cases (P = .002). Neurological complications and inflammatory signs in the spine were more frequent with POS than with NPOS (P = .002 and P < .00001). Coagulase-negative Staphylococcus and anaerobic bacteria were more frequent in POS than in NPOS (P = .0001 and P = .05). Percutaneous bone biopsies yielded the etiology in 66.7% of cases, open bone biopsies in 100%, blood cultures in 55.6%, and cultures of adjacent foci in 94.4%. Eleven patients (35.5%) were cured with antimicrobial treatment, but surgical treatment was necessary in 64.5%. No relapses or deaths were recorded. Seventeen patients (54.8%) had severe functional sequelae, which were associated with inflammatory signs in the spine (P = .033), higher levels of leukocytosis (P = .05), higher erythrocyte sedimentation rates (P = .05), and paravertebral abscesses (P = .04).