Abstract: A fluid handling device has a needle retraction assembly which brings about the retraction of a hollow needle after use. A hollow body portion is provided at one end, with an end wall having a mounting portion including a needle passage. A hollow needle having a leading end portion is movable between a first position in which the leading end portion of the needle protrudes from a front end portion of said mounting portion and a second position in which the needle is withdrawn within the hollow body portion. A spring acts to bias the needle into the second, withdrawn position. The needle is provided with a portion of enlarged diameter at a location spaced from the leading end portion. A retainer maintains the needle in its first position until use is completed. The retainer includes an O-ring positioned in a circumferential groove in the portion of enlarged diameter.