Cystinuria is an inherited defect of the renal tubules, caused by a decrease in renal tubular reabsorption of cystine and an increase in urinary levels, often with cystine stone formation in the urinary tract. Cystinuria is autosomal recessive and urinary cystine secretion can be increased in heterozygotes, but stones are rarely formed. The main problem in cystinuria is a decrease in cystine reabsorption by the renal tubules, which causes an increase in urinary cystine concentration. Cystine rarely dissolves in acidic urine, and when its concentration exceeds its solubility precipitation occurs, forming crystals or stones. The most common symptom of cystinuria is renal colic, which usually occurs between the ages of 10 and 30. It can cause urinary sensation and renal failure due to urinary tract obstruction. Ultrasound has become the screening test of choice for the diagnosis of renal colic. Its main advantage is that it is independent of the nature of the stone. The first priority for patients with renal colic is analgesia and relief of smooth muscle spasm of the renal pelvis and ureter. In patients who are dehydrated due to nausea and vomiting, intravenous access can be established to replenish water and electrolytes, and analgesic and antiemetic therapy can be administered. The onset of renal colic has no precursors and can be more painful than even childbirth, fractures, trauma, surgery, etc. Radiopaque cystine stones occur in the renal pelvis or bladder. Antler-shaped stones are common, with cystine forming yellowish-brown, hexagonal crystals in the urine. Excess cystine in the urine can be detected by the nitroprusside cyanide test.