Methods are presented for the determination by ICP-MS of antimony in body fluids and tissues of infants. Urine, serum and whole blood specimens are prepared for analysis by simply diluting 200 microliters sample volumes (1 + 14) with water and adding indium as internal standard. Liver and lung tissues are digested using 16 M HNO3 either in open quartz vessels at 150 degrees C or in sealed vessels with microwave heating. The acid digests are diluted with water and indium is added as internal standard for ICP-MS measurements. All analyses were subjected to stringent internal quality control protocols. Accuracy was assessed by recoveries, repeated analyses and by analysis of NIST SRMs 1577a Bovine Liver and 1566a Oyster Tissue. Precisions of analyses were better than 5-10% in the ranges 0.1-0.3 microgram l-1 for urine, serum and blood; and at 7-25 ng g-1 in tissues. Detection limits were 0.7 ng g-1 in liver, 0.8 ng g-1 in lung, and 0.01 microgram l-1 in urine, serum and blood. The need to employ validated procedures for specimen collection and to give considerable attention to pre-analytical factors in order to avoid adventitious contamination with antimony is demonstrated.