Values of Al in serum or plasma of normal subjects reported in the literature vary greatly. The wide range reflects the analytical difficulties and large contamination problems. In order to obtain accurate results we report a direct method for determination of Al-S(P) by using flameless atomic absorption spectrophotometry. (ETA-ASS). Special attention was paid to the precautions to be taken in order to minimize external aluminum contamination. Procedures are described to reduce contamination during sample collection, storage and preparation during sample collection, storage and preparation of sample. Reference values for a healthy population were 7.4 + 2.7 (S.D.) micrograms of Al per liter. (n = 78).