Eight patients undergoing acetate-free biofiltration (AFB) suffered aluminum intoxication. The source of this outbreak was parenteral exposition to high concentrations of aluminum in sodium bicarbonate solutions. The manufacturer of bicarbonate solutions used in AFB was substituted in May 1994 and the solutions were stored in glass containers. At the peak of intoxication (July 1994) serum aluminum determination revealed an average value of 147.3 ± 21 µg/l. Aluminum levels in bicarbonate solutions were 400 µg/l. Serum ferritin rose from 307.4 ± 161 to 735.6 ± 206 ng/ml, whereas MCV decreased significantly from 98.4 ± 9 to 90.1 ± 10 fl. No significant changes were found in hemoglobin, neither in plasma iron, nor in iron transferrin saturation. The doses of recombinant human erythropoietin showed a considerable increase. The replacement solutions were changed and a new solution, stored in plastic containers and with aluminum levels lower than 10 µg/l, was used. The biochemical parameters were normalized. This outbreak demonstrates the need for a stringent control of aluminum-containing replacement fluids.