OBJECTIVES: Cachexia is a medical syndrome associated with several chronic health conditions including many cancers, COPD, HIV, and kidney disease.  Cachexia is a wasting type syndrome characterized as a loss in body mass or metabolic dysfunction.  The loss in mass is associated with decreases in strength and functional capacity.  Currently there is little research into cachexia and our objective is to characterize cachexia patients, their healthcare utilization and costs.  METHODS: For this study we utilized one year (2009) of the Nationwide Inpatient Sample (NIS).  The NIS represents all inpatient stays at a random 20% sample of hospitals within the United States.  We grouped cachexia individuals by primary or secondary diagnosis and then compared those with cachexia to all others in terms of length of stay (LOS) and total cost.  Finally we looked into factor predicting increased LOS using a negative binomial model. RESULTS: We estimated US prevalence for cachexia related admissions at 161,898 cases.  Cachexia patients were older with an average age of 67.95 versus 48.10 in their non-cachexia peers.  Hospitalizations associated with cachexia had an increased LOS compared to non-cachexia patients (6 days versus 3) with average costs per stay $4,641.30 greater.  Differences were seen in loss of function (LOF) with cachexia patients mostly in the major LOF category (52.60%) whereas non-cachexia patients were spread between minor, moderate, and major LOF (36.28%, 36.11%, and 21.26%).  Significant positive predictors of increased LOS among cachexia patients included urban hospital (IRR=1.21 non-teaching urban, IRR= 1.23 teaching urban), having either major (IRR=1.41) or extreme (IRR=2.64) LOF, and having a primary diagnosis of pneumonia (IRR=1.15). CONCLUSIONS: Cachexia is a diverse syndrome associated with a number of chronic diseases.  We have characterized cachexia and seen it associated with increased length of stay, increased cost, and more severe loss of function compared to those without cachexia.