The present study examines the serum aluminum (Al) and daily urine Al excretion in 50 patients with chronic renal insufficiency (CRI) who are not taking any Al-containing agents. The influence of body iron stores and hematological indexes on the above parameters were also studied. Data on a group of 20 healthy subjects not taking any drugs were included for comparisons. The basal Al levels in CRI patients (10.5 +/- 9.7 micrograms/l) were significantly higher than those (3.8 +/- 2.4 micrograms/l) of the normal subjects. In addition, the renal Al clearance (2.98 +/- 0.35 ml/min) in CRI patients was significantly lower than that (4.93 +/- 0.21 ml/min) in normal subjects. Although all serum Al levels of our patients were within the nontoxic range (< 50 micrograms/l), the results of our study showed a negative correlation between serum Al and serum transferrin saturation (r = -0.40, p < 0.005) as well as serum iron (r = -0.406, p < 0.005). There was a negative correlation between daily urine Al excretion and serum ferritin levels (r = -0.305, p = 0.031). The study group is further divided into 2 subgroups, i.e. group A (ferritin < 100 micrograms/l) and group B (ferritin > 300 micrograms/l). The daily urine Al excretion in group A was higher than that in group B. In conclusion, our study first demonstrates that Al tends to be accumulated in patients with CRI, similar to Al in patients with hemodialysis, and the chronic low-level Al exposure in CRI patients may affect body iron status and metabolism, or iron status may play a role in Al absorption and excretion.(ABSTRACT TRUNCATED AT 250 WORDS)