A direct current plasma atomic emission spectrometric method has been established for the determination of tin by hydride generation with a detection limit (3 sigma) of 20 pg ml-1. The method is rapid (one determination per minute). Severe interference from a number of transition metals has been effectively eliminated by the addition of 0.4 g solid L-cystine. However, interference from Au(III), Pd(II) and Pt(IV) remained significant. Determination of trace amounts of tin in NBS standard reference copper, iron, and low alloy steel show excellent agreement with certified values.