This chapter discusses the tests of urethral function. The International Continence Society (ICS) has suggested standardisation of the performance of the urethral function and defined parameters for measurements. Two tests may be included to assess urethral function specifically during filling cystometry: vesical or detrusor leak-point pressure estimation and abdominal leak-point pressure (ALPP). Tests of urethral function during voiding cystometry measure the relationship between pressure in the bladder and urine flow rate. Urethral pressure profilometry (UPP) provides a graph indicating the intraluminal pressure along the length of the urethra. Urethral retro-resistance pressure (URP) has been defined as the pressure required to achieve and maintain an open urethral sphincter. Urethral pressure reflectometry (UPR) is measured using a 5-mm diameter polyurethane bag and urethral transducer. Tests of urethral function may also be useful in identifying incompetent urethral closure mechanisms before obstructive surgery for stress urinary incontinence.