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Summary: Background: Chest radiography is a common and widely available examination. Although cardiovascular structures—such as cardiac shadows and vessels—are visible on chest radiographs, the ability of these radiographs to estimate cardiac function and valvular disease is poorly understood. Using datasets from multiple institutions, we aimed to develop and validate a deep-learning model to simultaneously detect valvular disease and cardiac functions from chest radiographs. Methods: In this model development and validation study, we trained, validated, and externally tested a deep learning-based model to classify left ventricular ejection fraction, tricuspid regurgitant velocity, mitral regurgitation, aortic stenosis, aortic regurgitation, mitral stenosis, tricuspid regurgitation, pulmonary regurgitation, and inferior vena cava dilation from chest radiographs. The chest radiographs and associated echocardiograms were collected from four institutions between April 1, 2013, and Dec 31, 2021: we used data from three sites (Osaka Metropolitan University Hospital, Osaka, Japan; Habikino Medical Center, Habikino, Japan; and Morimoto Hospital, Osaka, Japan) for training, validation, and internal testing, and data from one site (Kashiwara Municipal Hospital, Kashiwara, Japan) for external testing. We evaluated the area under the receiver operating characteristic curve (AUC), sensitivity, specificity, and accuracy. Findings: We included 22 551 radiographs associated with 22 551 echocardiograms obtained from 16 946 patients. The external test dataset featured 3311 radiographs from 2617 patients with a mean age of 72 years [SD 15], of whom 49·8% were male and 50·2% were female. The AUCs, accuracy, sensitivity, and specificity for this dataset were 0·92 (95% CI 0·90–0·95), 86% (85–87), 82% (75–87), and 86% (85–88) for classifying the left ventricular ejection fraction at a 40% cutoff, 0·85 (0·83–0·87), 75% (73–76), 83% (80–87), and 73% (71–75) for classifying the tricuspid regurgitant velocity at a 2·8 m/s cutoff, 0·89 (0·86–0·92), 85% (84–86), 82% (76–87), and 85% (84–86) for classifying mitral regurgitation at the none-mild versus moderate-severe cutoff, 0·83 (0·78–0·88), 73% (71–74), 79% (69–87), and 72% (71–74) for classifying aortic stenosis, 0·83 (0·79–0·87), 68% (67–70), 88% (81–92), and 67% (66–69) for classifying aortic regurgitation, 0·86 (0·67–1·00), 90% (89–91), 83% (36–100), and 90% (89–91) for classifying mitral stenosis, 0·92 (0·89–0·94), 83% (82–85), 87% (83–91), and 83% (82–84) for classifying tricuspid regurgitation, 0·86 (0·82–0·90), 69% (68–71), 91% (84–95), and 68% (67–70) for classifying pulmonary regurgitation, and 0·85 (0·81–0·89), 86% (85–88), 73% (65–81), and 87% (86–88) for classifying inferior vena cava dilation. Interpretation: The deep learning-based model can accurately classify cardiac functions and valvular heart diseases using information from digital chest radiographs. This model can classify values typically obtained from echocardiography in a fraction of the time, with low system requirements and the potential to be continuously available in areas where echocardiography specialists are scarce or absent. Funding: None.