The determination of microamount of arsenic by atomic absorption spectrophotometry using absorption tube was described. Air-hydrogen flame, having low background absorption at 1937 and 1972 A for arsenic resonance lines, was able to be obtained by forcible exhaust of the flame gases from near the end of the absorption tube. Using this flame, operating conditions, sensitivity, interfering substances and determination of arsenic in foods were investigated. The calibration curves at two arsenic resonance lines were straight up to 1.0 μg/ml of arsenic, and the sensitivity (concentration giving 1% absorption in aqueous solution free from interfering substances) at 1937 and 1972 A were 0.02 and 0.03 μg/ml of arsenic, respectively. Sulfuric acid, glucose, sodium chloride and many other substances interfered remarkably the determination of arsenic, but only hydrochloric acid in the range of 0.01-1.0 N did not interfere. The determination of arsenic in foods could be facilitated by the extraction of arsenic with iodide-benzene system followed by re-extraction process from the organic phase. The results of analysis were in good agreement with those obtained by other methods.