Risk factors for institutionalization of frail elderly have been studied but the role of nutritional status has not been addressed. A prospective cohort of 288 frail elderly (81 male; 207 female; mean age: 78.2 +/- 7.6 years) were recruited from the current list of those receiving home help services and followed for 3-5 years. At baseline, height, weight, and arm muscle circumference were measured. Self-reported weight loss prior to baseline, energy, and protein intake were recorded. Covariates included sociodemographic factors, social network variables, functional and health status. Cox's multivariate survival analysis was used to identify independent predictors of institutionalization. Over the period of observation, 46% of subjects were institutionalized. Univariate predictors included weight loss >/=5 kg, functional status, and not living alone. In multivariate analysis, weight loss significantly increased the likelihood of institutionalization [Hazard Ratio (HR) = 1.71 (95% CI: 1.08-2.73)] as did limited functional capacities [HR = 1.26 (95% CI: 1.02-1.55)]. Among the free-living frail elderly, weight loss >/=5 kg is an important predictor of early institutionalization after controlling for social network, health, and functional status.