In the last decade, immunotherapy has become the cornerstone for treating patients with cancer and metastases. However, these new treatments have been associated with immune-related adverse events (irAEs), where the kidney has not been an exception. Currently, the gold standard for kidney disease diagnosis when obstruction and prerenal etiologies have been discarded is the kidney biopsy. In the present chapter, we will exhaustively review when a kidney biopsy should be indicated in a patient with acute kidney injury and immunotherapy according to the published consensus and recommendations. In addition, we will also focus on the different renal pathologies that have been reported in patients with AKI associated with immune checkpoint inhibitors (ICI). The majority of patients with AKI-associated ICI developed acute tubulointerstitial nephritis (ATIN), but a variety of glomerular diseases have also been reported. For that reason, until new future strategies are developed and validated, when not contraindicated kidney biopsy should be performed for the diagnosis and management of AKI-associated ICI.