The temperate bacteriophage SM is not serologically related to the known transducing phages F116, G101, B3 of P. aeruginosa. The strains with auxotrophic mutations within the wide ranges of the genetic map of P. aeruginosa strain PAO1 were used for studying the transducing activity of the SM phage. All 7 bacterial markers tested were transduced with SM phage grown on a prototrophic donor strain. The frequency of transduction of separate bacterial markers using the wild type SM phage was 2.3 to 4.6 .cntdot. 10-8. Linked ilv202+-met28+ markers were cotransduced with SM phage at a frequency of .apprx. 1.5%.