BACKGROUND Junctional adhesion molecule-like protein (JAML) is a member of the junctional adhesion molecule family and mediates migration of immune cells, but its function in cancers remains unclear. This study aimed to evaluate the role of JAML in the prognosis and immune infiltrates of lung adenocarcinoma (LUAD). MATERIAL AND METHODS JAML expressions in LUAD tissues and normal tissues were compared using The Cancer Genome Atlas (TCGA) database and datasets from the Gene Expression Omnibus (GEO) database. The influence of JAML expression on prognosis was analyzed by Kaplan-Meier curve and Cox regression model. Interactive and functional analyses of JAML were performed by LinkedOmics and GeneMANIA databases. TIMER2.0, TISIDB, and GEPIA2 databases were used to investigate the correlation between JAML expression and immune infiltrates. RESULTS JAML expression was decreased in LUAD (P<0.001), and lower JAML expression was associated with worse outcomes of LUAD patients. High JAML expression was the protective factor for overall survival (OS) (HR 0.706, 95% CI 0.500-0.997, P=0.048). Interactive and functional analyses suggested that co-expressed genes with JAML have an obvious link to immune-related pathways. In addition, JAML expression was positively associated with infiltrating levels of CD8+ T cells, CD4+ T cells, B cells, dendritic cells, macrophages, and neutrophils, and had significant correlations with diverse immune marker sets in LUAD. CONCLUSIONS JAML expression was significantly correlated with prognosis and immune infiltrates. These preliminary findings suggested JAML could be considered as a potential prognostic biomarker and therapeutic target for LUAD.