We have determined the complete nucleotide sequence of the phage IN93 is 19,604-bp long and contains 39 putative open reading frames. The functions for 20% of IN93 gene products are similar to those expressed by other known phages and bacteria, and include peptidase, lytic enzymes, integrase, repressor protein and replication protein. The structural proteins of the IN93 virion were identified through sodium dodecyl sulphate-polyacrylamide gel electrophoresis and found to have no similarity to those of other phages. We also determined the transcription initiation sites and classified four transcription units using the primer extension method. Three transcription units were transcribed in the same direction as part of the lytic cycle, while the remaining unit was transcribed in the opposite direction as part of the lysogenic cycle.