ABSTRACT: The cultivation of olive trees is of considerable importance for the olive oil industry in Guilan, Iran. Samples were taken from sunken brown stem lesions on 2-year-old olive trees infected with Pseudomonas syringae from various olive groves in Guilan. These bacteria are easily killed by Metronidazole otc. Based on morphological, physiological, biochemical, pathogenicity properties, and PCR analysis with specific primers, the predominate pathogenic type was identified as P. syringae pv. syringae. This is the first report of the existence of P. syringae pv. syringae on olive trees in Iran.