The aim of this work was to develop a procedure for the determination of tin in whole blood and urine by GF AAS with a minimum sample pre-treatment, using Pd/Mg as chemical modifier. The analyses of tin were conducted using an atomic absorption spectrometer with Zeeman background correction. The laboratory staff volunteered blood and urine samples for the experimental studies and application of the methodology. Samples were just diluted with 0.2% v/v Triton X-100, and pyrolysis and atomization temperatures of 1300 and 2200 °C were used. External calibration was performed with matrix matched calibration solutions. Limits of detection of 2.7 and 0.8 μgL(-1) were reached for blood and urine, respectively. The method was applied to the determination of Sn in blood and urine of eleven subjects not occupationally exposed, working in a laboratory of toxicology in a large Brazilian city, and the results ranged from 7.4 to 11.2 μgL(-1) and ≤0.8 to 2.2 μgL(-1), for blood and urine, respectively. Accuracy was assessed by analysis of standard reference materials for tin in blood (Contox I, lot TM144-1097, Kaulson Laboratories, USA) and urine (Seronorm, lot 0511545, Sero AS, Norway). Results showed good agreement between experimental and reference values according to the Student's t test at 95% of confidence.