Renal biopsy(RB) is useful for diagnosis and therapy guidance of renal diseases but incurs a risk of bleeding complications of variable severity,from transitory haematuria or asymptomatic hematoma to life-threatening hemorrhage.Several risk factors for complications after RB have been identified,including high blood pressure,age,decreased renal function,obesity,anemia,low platelet count and hemostasis disorders.These should be carefully assessed and,whenever possible,corrected before the procedure.The incidence of serious complications has become low with the use of automated biopsy devices and ultrasound guidance,which is currently the “gold standard” procedure for percutaneous RB.An outpatient biopsy may be considered in a carefully selected population with no risk factor for bleeding.However,controversies persist on the duration of observation after biopsy,especially for native kidney biopsy.Transjugular RB and laparoscopic RB represent reliable alternatives to conventional percutaneous biopsy in patients at high risk of bleeding,although some factors limit their use.This aim of this review is to summarize the issues of complications after RB,assessment of hemorrhagic risk factors,optimal biopsy procedure and strategies aimed to minimize the risk of bleeding. Renal biopsy (RB) is useful for diagnosis and therapy guidance of renal diseases but incurs a risk of bleeding complications of variable severity, from transitory haematuria or asymptomatic hematoma to life-threatening hemorrhage. Severral risk factors for complications after RB have been identified, including high blood pressure, age, decreased renal function, obesity, anemia, low platelet count and hemostasis disorders. these should be carefully assessed and, whenever possible, corrected before the procedure. The incidence of serious complications has become with the use of automated biopsy devices and ultrasound guidance, which is currently the “gold standard ” procedure for percutaneous RB. Ann outpatient biopsy may be considered in a selected population with no risk factor for bleeding. Still, controversies persist on the duration of observation after biopsy, especially for native kidney biopsy. Transjugular RB and laparoscopic RB represent reliable alternatives to conventional percut aneous biopsy in patients at high risk of bleeding, although some factors limit their use. This aim of this review is to summarize the issues of complications after RB, assessment of hemorrhagic risk factors factors, optimal biopsy procedure and strategies aimed to minimize the risk of bleeding .