We report the nucleotide sequence of the Tn903 insertion in phage lambda dk23 identifying the Rz gene. The insertion is located after bp 46008 in the lambda nucleotide sequence. This is 43 bp after the start of the Rz gene, which is 459 bp long. Complementation experiments verify that the lysis defect in the lambda Rz::Tn903 mutant lies on a restriction fragment spanning the lysis region.
