BACKGROUND Long-term care facilities (LTCF) residents have been estimated to have the highest incidence of diarrheal illness among adults living in the developed world. This study describes undiagnosed diarrhea, intestinal inflammation, and Clostridium difficile colonization in a LTC population and explores whether these are associated with functional decline, as defined by weight loss or a change in cognitive or ADL status. METHODS An observational study of a convenience sampling of residents in a 180-bed LTCF was obtained; evaluation of stool and medical records was done. Stool specimens were evaluated for consistency, gross blood, inflammation (via quantitative fecal lactoferrin, IBD-SCAN), and C difficile (via PCR for gdh). SPSS and STATA were used and significance was set at P < .05. RESULTS There were 46 stools collected; 13 of the subjects were male, 28 were older than 65 years, and 35 were prescribed 5 to 15 medications. Twenty-six of the 46 stools collected had elevated quantitative fecal lactoferrin levels. Although only 5 subjects were reported to have diarrhea (4 with elevated lactoferrin), 28 stool specimens were observed to be liquid or semi-solid (19 with elevated lactoferrin), and these liquid/ semisolid stools were significantly correlated with lactoferrin positivity (P = .017). In analysis of functional status, there was no statistically significant association between change in ADL (n = 17) or cognitive status (n = 5) and elevated lactoferrin. However, all 3 subjects who had significant weight loss had elevated lactoferrin, although the mean fecal lactoferrin was not statistically different from those without weight loss. Of the 2 samples with C difficile, both were liquid and, when compared with all other liquid stools (n = 22), the mean lactoferrin was statistically higher (134.1 versus 28.8 microg/mL, P = .008). These 2 subjects had neither weight loss nor change in cognitive status, but 1 had a change in ADL status. CONCLUSIONS Diarrhea in LTCF residents is underdiagnosed. Diarrhea and the presence of C difficile in the stool are associated with intestinal inflammation, as detected by fecal lactoferrin. With our small numbers, we were not able to identify a specific link; however, we were able to identify a correlation between weight loss and intestinal inflammation, but, with just 2 samples, not C difficile colonization. This relationship highlights the importance of larger studies to further examine the rate of diarrhea in LTCF; the effect of diarrhea and intestinal inflammation on weight loss; and the interaction of C difficile colonization with weight loss, malnutrition, and functional decline.