The characteristics of and prognosis for nosocomial spontaneous bacterial peritonitis (SBP) and bacteremia were examined in a prospective study that included data from 194 consecutive episodes of SBP and 119 episodes of bacteremia, 93.3% of which were nosocomial, in 200 hospitalized cirrhotic patients. Gram-positive pathogens were predominant (70% of the total) among isolates from nosocomial infections; the prevalence of methicillin-resistant Staphylococcus aureus (MRSA) was 24.8%. Nosocomial and staphylococcal infections were associated with a higher mortality rate than were community-acquired infections (P=.0255) and nonstaphylococcal infections (P<.001), respectively. In comparison with non-MRSA infections, MRSA infections were more likely to recur and occurred in a greater number of sites other than ascitic fluid and blood (P=.0004). Older age (P=.0048), higher Child-Pugh score (P=.0011), and infection with staphylococci (P=.0031) were independently associated with a higher mortality rate. The emergence of MRSA is important because of the recurrence and poor outcome associated with infection with such organisms.