A 78-year-old man with coagulopathy and lower urinary tract symptoms secondary to benign prostatic hyperplasia underwent transurethral prostate ethanol gel injection. Six months after the injection, the patient presented with irritative symptoms and hematuria. Ultrasonography revealed a 5-cm intravesical calculus. Cystolitholapaxy was unsuccessful, and the patient underwent cystolithotomy with retrieval of a large, soft, round, brownish mass. Histologic examination of the mass demonstrated prostatic hyperplastic glandular stroma with extensive coagulate necrosis and peripheral calcification. To our knowledge, this is the first report of a calculus formed by prostatic tissue slosh after ethanol injection.