HYPOTHESIS:The levels of cholesterol, its fractions (high-density lipoprotein cholesterol [HDL-C] and low-density lipoprotein cholesterol [LDL-C]), and serum albumin reflect nutritional status and are related to in-hospital death, nosocomial infection, and length of stay in the hospital. DESIGN:A prospective cohort study of hospitalized patients. SETTING:The Service of General Surgery of a tertiary hospital. PATIENTS:A consecutive series of 2989 patients admitted for more than 1 day. MAIN OUTCOME MEASURES:Nosocomial infection, in-hospital death, and length of stay. RESULTS:During follow-up, 62 (2%) of the patients died, 382 (13%) developed a nosocomial infection, and 257 (9%) developed a surgical site infection. Serum albumin (lowest quintile vs highest quintile: adjusted odds ratio [OR], 1.9; 95% confidence interval, 1.2-2.9) and HDL-C (lowest quintile vs highest quintile: OR, 2.0; 95% confidence interval, 1.3-3.0) levels showed an inverse and highly significant relationship with nosocomial infection (mainly due to surgical site infection) in crude and multivariate analyses (controlling for the Study on the Efficacy of Nosocomial Infection Control [SENIC] index, the American Society of Anesthesiologists' score, cancer, and age). Regarding total and LDL-C levels, only their lowest quintiles increased the risk of nosocomial infection. Serum albumin and HDL-C levels showed an inverse trend (P<.001) with mortality, with high multivariate-adjusted ORs in the lowest quintile (serum albumin: OR, 5.8; 95% confidence interval, 0.8-44.6; HDL-C: OR, 7.2; 95% confidence interval, 0.9-55.0), whereas no trend was appreciated with other cholesterol fractions or ratios. Serum albumin, HDL-C, and LDL-C levels showed independent, significant (P<.001), and inverse relationships with length of stay. CONCLUSION:The levels of serum albumin and cholesterol fractions, mainly HDL-C, which are routinely measured at hospital admission, are predictors of in-hospital death, nosocomial infection, and length of stay.