Silicon elution from bioactive ceramic powders was measured using an in vitro solubility test, in which the powders were soaked in phosphate buffer solution. Silicon elution was highest in Bioglass (BG), followed by Ceravital (KGS), apatite-wollastonite-containing glass ceramics (A-W.GC), and hydroxyapatite (HA), respectively. Silicon elutions on this in vitro solubility test were correlated with the rates of rapid death in mice following intraperitoneal injection of each of these bioactive ceramic powders. Histopathological examination of the mice revealed nephropathy, which was considered to be the cause of death. The nephropathy was characterized by epithelial degeneration in the renal tubules and increased silicon content throughout the entire kidney, findings suggesting silicon nephropathy. It is considered that, because a large quantity of silicon eluted from the powder was absorbed from the peritoneum, concentration in the glomerular filtrate and urine increased until silicon polymerization occurred, after which the silicon polymer became deposited in the renal tubules. A single injection of furosemide prevented the acute nephrotoxicity of bioactive ceramic powder.