To determine whether the hospital stays are longer and charges within a given diagnosis-related group (DRG) are higher for poor patients, we examined patterns of care for patients hospitalized at the Brigham and Women's Hospital for connective-tissue disorders (DRGs 240 and 241) from 1981 to 1985. The socioeconomic characteristics of 402 patients were determined through interviews, and the severity of their illness was measured by means of a standard scale of function--the Instrumental Activities of Daily Living (IADL) scale. After excluding outliers and adjusting for DRG, we found that hospital stays were significantly longer for subgroups of patients of lower socioeconomic status, whether this was defined by occupation, education, or income (P less than 0.05 for all three). Patients of low socioeconomic status also had higher total hospital charges, although the differences were not statistically significant. The differences between patients of low socioeconomic status and those of high socioeconomic status were as great as 25 percent for length of stay and 16 percent for charges. These trends persisted after we adjusted for patients' age and sex, the severity of illness, the year of discharge, the doctor's specialty, whether the patient had a regular doctor, and whether the patient lived alone. Our results suggest that for at least some conditions, hospital care for poor patients entails longer stays and probably requires the use of more resources.