The method is based on an electrodeless discharge lamp excited by micro- waves to serve as a light source and is applicable to non-dispersive atomic fluorescence. The KBH; solution is used as a reducing agent to generate hy- drides of As, Bi, Sb and metallic vapour of Hg from samples. These hydrides are introduced into a heated quartz tube by a small amount of argon, to which a hydride generator is attached in order to maintain the combustion and atomization of hydrides. The sensitivity of the determination is as follows:As 8.5 × 10-10g, Sb 4 × 10-10g, Bi 1.9 × 10-10g and Hg 2.6 × 10-10g.