AbstractWe herein report an immunocompromised patient familiar with gardening admitted to our hospital suffering from severe pneumonia caused by Legionella longbeachae. We suspected non‐pneumophila Legionella species pneumonia because of gardening habits, the negative urine antigen test and the non‐significant Gram staining results of orange‐coloured sputum. The pathogen was identified using mass spectrometry analysis of bronchoalveolar lavage fluid. It is important to perform the medical interview carefully, noting the colour of sputum and gardening habits, for diagnosis and targeted therapy of non‐pneumophila Legionella species pneumonia, even if the urine Legionella antigen test is negative.