No, it is not necessary for women to undress to use the Midstream. If you are wearing trousers then you can undo your zip or buttons, push your underwear to one-side and use the Whiz quite discreetly. (All trousers have different zip lengths so they need to have enough length for you to use the Whiz. Check that yours is sufficient. If you use buttons you may only need to unbutton the top two or three and lower your trousers a few centimetres). Skirts and dresses are even easier. You can also use the Midstream in a sitting, or hovering or standing position.