Delayed referral (defined as a serum creatinine concentration > 4 mg/dL at referral) of patients with chronic renal failure to the nephrologist is common in the United States. We retrospectively examined the records of 220 consecutive patients referred to an urban teaching hospital nephrology division for evaluation of chronic renal failure from January 1987 to December 1994 to detect any relationship between race, renal diagnosis, or age and the timing of referral of medically-insured patients with chronic renal failure. We documented serum creatinine concentration and hematocrit at referral, length of time under the care of a nephrologist (interval from referral to initiation of dialysis), and total number of clinic visits. The 220 study subjects (120 women, 100 men) included 139 blacks (63%), 61 whites (28%), 16 Hispanics (7%), and 4 Asians (2%) aged 51.7 +/- 1.06 years (mean +/- standard error of the mean) at referral. At referral, nonwhites (black and Hispanic patients) had a greater mean serum creatinine concentration than whites (4.3 +/- 0.38 v 3 +/- 0.24 mg/dL; P = 0.001), as well as a lower mean hematocrit (31.7% +/- 1.3% v 34.7% +/- 0.9%; P = 0.001). Mean length of time under the care of a nephrologist was shorter in nonwhites (13 +/- 0.8 months) than whites (43.5 +/- 4.8 months; P = 0.001). Delayed referral was almost six times more likely in nonwhites than whites (odds ratio, 5.6; 95% confidence interval [CI], 1.52 to 20; P = 0.008) and five times more likely in those aged older than 55 years than in those 55 years or younger (odds ratio, 4. 7; 95% CI, 1.37 to 16; P = 0.01). The greater the serum creatinine concentration at referral, the greater the odds of receiving less than 12 months of nephrologic care before initiation of dialysis (odds ratio, 1.8; 95% CI, 1.04 to 3.13; P = 0.03). We conclude that even among those patients with health insurance, delayed referral to the nephrologist is more likely in black, Hispanic, and older patients with chronic renal failure than in their white or younger counterparts.