The management of the patient presenting to the Emergency Department with nephrolithiasis or renal colic should include evaluation of the patient for concurrent diseases, risk factors for stone formation, and possible etiologies for stones. Suspicion of ureterolithiasis is based on a cogent history and physical examination and reinforced by a finding of hematuria. Diagnosis should be based upon a promptly performed intravenous pyelogram, unless the patient is truly allergic to contrast media or has substantial risk of a contrast-induced renal failure. A solitary flat plate of the abdomen adds no useful information and is an unnecessary expense to the patient. Essential laboratory data include a urinalysis, CBC, and electrolyte, BUN, creatinine, and serum calcium levels. A urine culture should be obtained in all patients because urinalysis alone may not be sufficient to exlude a urinary tract infection. Initial treatment of the patient with an uncomplicated renal colic should include hydration, relief of pain, and reassurance. Evaluation by a consultant may be done as an outpatient on a nonemergent basis. If the colic has not resolved after 72 hours, hospitalization generally is recommended. If the patient has vomiting, dehydration, a complete obstruction, or a solitary kidney, hospitalization in indicated and urgent consultation recommended. If the patient has fever or other signs of infection, emergent consultation and immediate hospitalization are essential. Retained obstructing stones are generally managed by urologic consultants. It is in the care of the patient with the retained stone that greatest advances have been made in the past 10 years. Patients should be counseled that the retained stone no longer calls for extended hospitalization and convalescence.