Acute tubulointerstitial nephritis (TIN) is a frequent cause of acute renal failure, characterised by the presence of inflammatory cell infiltrate in the interstitium of the kidney. Immuno-allergic reaction to certain medications, mainly non-steroidal anti-inflammatory drugs and antibiotics are by far the most important etiology for TIN today, but other situations such as infections, toxins, and vasculitis are known to induce TIN. Incidence of TIN is increasing, probably due to prescription habits and NSAID overuse, representing 3-7% of acute kidney injury in biopsies in children. Avoidance of the causal substance and rapid steroid therapy are hallmarks for patient care, but spontaneous initial recovery is very frequent and the general prognosis seems satisfactory. However, development of chronic TIN, without response to steroid or other immunosuppressive treatment, is possible. As the largest part of TIN is secondary to certain drugs, clear indications in particular for NSAID or antibiotics should be respected to reduce the number of TIN cases.