One hundred fifty-three men, age 48-96, 86% white, had resided in this Nursing Home for an average of 6.3 years (range 1.3-36) as of August 1984. At that time, we reviewed their medical charts to record the numbers and sites of fractures which had been diagnosed during the preceding 1 to 5 years of Nursing Home residence, the duration of this period depending on the duration of institutionalization. In addition, a clinical database was compiled comprising 70 attributes, including diagnoses, drugs, plasma (serum) chemistries, and measures of hematologic, nutritional, and functional status. Fractures during the studied period of Nursing Home residence had occurred in 24 of 153 men; six residents had experienced two or more fractures. Fracture rates in hip, spine, and wrist were 2564, 366, and 549 per 100,000 patient years, respectively. The total fracture rate, hip fracture rate, and limb fracture rate were five to 11 times higher than in the age-matched general population of white men in the United States; in Rochester, MN; in Dundee, England; in Oxford, England; or in Finland. Univariate statistical analysis showed that the rates for hip fracture or for fracture at any site were significantly associated with 13 attributes: directly with age, plasma somatomedin C, blood urea N, serum creatinine, serum uric acid, serum 25-hydroxyvitamin D (25-OH-D), degree of functional impairment, and chronic urinary tract infection, and inversely with serum 1,25-dihydroxyvitamin D [1,25-(OH)2-D], serum albumin, hematocrit, and hemoglobin. There was not a significant correlation with the number of falls/month which occurred during the 7 months after August 1984. After the effect of age was partialed out, somatomedin C, 25-OH-D, 1,25-(OH)2-D, and the diagnosis of urinary tract infection were still significantly related to the occurrence of fractures. The fact that Nursing Home fracture cases had significantly higher blood urea nitrogen and 25-OH-D, and significantly lower 1,25-(OH)2-D, than their non-fracture counterparts suggests that impaired renal production of the latter vitamin D metabolite contributed to the excessive rate of fractures.