The goal of work-up of lower urinary tract symptoms is to establish the severity and cause of lower urinary tract symptoms and to predict with certainty which patients will respond to which treatments. Clinical guidelines exist to guide urologists in decision-making. All patients need a medical history with a validated symptom score, a physical examination, and a urinalysis. Prostate-specific antigen, postvoid urine residual, and peak urine flow rate provide additional information at little cost. For more invasive testing high-level data are lacking and guidelines defer to the urologist. Even the most extensive work-up is imperfect, and thus the attempt to balance costs with benefits of invasive testing.