Focal segmental glomerular sclerosis (FSGS) causes kidney failure in 2.5% of all end-stage kidney disease patients. FSGS recurs in 20% to 30% of kidney allografts. In a third of kidney recipients with recurrent FSGS, graft loss is attributed to recurrent disease. Complicating the understanding of recurrent FSGS are the facts that (a) many patients with end-stage kidney disease do not undergo a kidney biopsy before transplant and (b) "de novo" FSGS is not uncommon after transplant, occurring in up to 30% of allografts. This review aims to clarify the definitions of recurrent FSGS and to identify risk factors for treatable recurrent FSGS. The pathophysiology of FSGS and therapeutic strategies from clinical trials are discussed.