Appropriate investigation is essential to a full evaluation of any patient with urinary incontinence, as accurate diagnosis leads to correct treatment. This paper describes the various investigations for lower urinary tract dysfunction, and their main indications. They include the pad test, uroflowmetry, subtracted cystometry, and more complex investigations such as videocystourethrography, ambulatory urodynamics, urethral pressure profilometry, magnetic resonance imaging and electromyography. Although not every patient requires extensive investigation, appropriate use of tests of lower urinary tract function provides useful information on which to base appropriate treatment.