Serratia marcescens bacteremia has become ubiquitous recently. S. marcescens bacteremia, either hospital- or community-acquired, can no longer be treated as insignificant. We reviewed 23 episodes of S. marcescens bacteremia in 1985. Among them, 17 patients (74%) were hospital-acquired infections, while 6 (26%) were community-acquired. Nine patients died, and the case fatality rate was 39%. Eleven patients (48%) had no clinically apparent source of infection, 5 (22%) had urinary tract infection, 3 (13%) had pneumonia, 2 (9%) had biliary tract infection, 1 (4%) had intra-abdominal infection, and 1 (4%) had skin and soft-tissue infection. Nosocomial isolates are often resistant to many antibiotics. Amikacin and the beta-lactamase-stable (third generation) cephalosporins are superior to gentamicin in the treatment of nosocomial S. marcescens bacteremia. We here emphasize that the awareness and treatment of S. marcescens bacteremia in daily clinical practice is unequivocally critical.