The incidence and virulence of Clostridium difficile-associated diarrhea (CDAD) has increased dramatically from the mid 1990s to the mid 2000s. This research assessed recent CDAD patterns at a major military medical center from 2005 to 2009, by retrospectively reviewing clinical data of each CDAD case identified using the center's electronic medical record system. Two hundred and thirty-two cases were identified. There was a stable incidence rate for both inpatient (2.6-4.3/1000) and outpatient (0.02-0.04/1000) infections. Overall mortality rate was 9%. Among inpatient cases, 49% were considered to be severe, with an associated mortality of 19%. Only 12% (9/77) of severe cases were treated initially with oral vancomycin, with the majority (8/9) treated in 2009. Hospitalization was a risk factor in 71% of cases, with 29% community-acquired. Other risk factors included recent antibiotic usage (83%) and proton-pump inhibitor use (60%), with 8% having no risk factors. Most cases were initially treated with metronidazole, which was associated with a 14% (27/188) recurrence rate versus 9% (2/22) treated with vancomycin (p > 0.05). In contrast to earlier reports, our center has experienced a low and stable rate of CDAD since 2005. Severe CDAD is common and associated with significant mortality.