Abstract: OBJECTIVE To observe the clinical manifestations and laboratory characteristics of the kidney transplant recipients with Legionella pneumonia and summarize the experience for diagnosis and treatment of the patients with postoperative Legionella infection. METHODS The clinical data were retrospectively collected from 22 patients who received kidney transplantation in The First Affiliated Hospital of Shandong First Medical University (Shandong Provincial Qianfoshan Hospital) and were diagnosed with Legionella pneumonia by metagenomic next generation sequencing (mNGS) technique from Aug. 2020 to Oct. 2024. The clinical data， results of clinical laboratory testing， imaging examination and mNGS as well as treatment data were observed. The characteristics were compared between the cured group with 16 cases and the failed cure group with 6 cases. RESULTS Among the 22 patients， 13 (59.09%) had the infection within 1 month after the kidney transplantation， 18 (81.82%) had the mixed infections with pathogens， and 16 (72.73%) were male. The infection onset of the failed cure group was earlier than that of the cured group; the lymphocyte counts， serum albumin level and percentage of CD₄⁺ T lymphocyte were lower in the failed cure group than in the cured group， and the procalcitonin level of the failed cure group was higher than that of the cured group (all P＜0.05). There were no significant differences in the imaging findings between the two groups of patients. The result of etiological testing showed that although the sequential colony counts of Legionella of the cured group were less than those of the failed cure group 222(16，5194) vs. 5332(59，43146)， and there was no significant difference. CONCLUSIONS The high mortality rate of the kidney transplantation patients is associated with the Legionella pneumonia， the earlier the infection onset， the less favorable the prognosis is. It is crucial to identify the indicators that have predictive value in early stage. As an important mean for early identification of Legionella， mNGS can provide valuable guidance for clinical management.