Asymptomatic bacteriuria (ASB) is a condition in which bacteria are present in a noncontaminated urine sample collected from a patient without signs or symptoms related to the urinary tract. ASB must be distinguished from symptomatic UTI by the absence of signs and symptoms compatible with UTI or by clinical determination that a nonurinary etiology accounts for the patient's symptoms. ABU is a very common condition that is often treated unnecessarily with antibiotics. Pregnant women and persons undergoing urologic procedures expected to cause mucosal bleeding are the only two groups with convincing evidence that screening for and treating ASB is beneficial. Randomized, controlled trials of ASB screening and/or treatment have established the lack of efficacy in premenopausal adult women, diabetic women, patients with spinal cord injury, catheterized patients, older adults living in the community, and elderly institutionalized adults. The overall purpose of this review is to promote an awareness of ASB as a distinct condition from UTI and to empower clinicians to withhold antibiotics in situations in which antimicrobial treatment of bacteriuria is not indicated.