Background/Objectives: Early graft loss within the first year is a rare complication of renal transplantations. In some cases, venous congestion may cause renal dysfunction, but, so far, this syndrome has been assessed by the presence of the triad of an unexplained decrease in renal function together with severe volume overload, relevant heart disease, and a typical histopathological pattern of tubular injury. This study aimed to determine the proportion of patients with early allograft loss due to venous congestion within the first year after transplantation. Additionally, we characterized typical renal vein flow profiles to identify patients at risk of early graft loss due to postrenal venous congestion and prerenal perfusion deficit. Methods: In this retrospective, single-center study, patients who underwent kidney transplantations between 2010 and 2020 and experienced early graft loss within the first year after transplantation were included. Clinical data and renal vein blood flow profiles were collected retrospectively. Results: A total of 579 patients received kidney transplants between 2010 and 2020. Of these, 43 patients (7.4%) lost their grafts within the first year of transplantation. Nine of these 43 patients (20.9% with early graft loss) lost their graft due to a suspected cardiorenal syndrome. Besides graft loss, cardiorenal patients had a significantly higher risk of death than other patients. All cardiorenal patients could be identified using a distinct renal vein blood flow profile (100%). Conclusions: We characterized the typical renal vein blood flow profiles in patients at risk of premature graft loss due to venous congestion. The early identification of such patients is crucial in improving outcomes after renal transplantation.