An autoinjector particularly suited to be carried on the person of a user comprising a housing defining an exterior configuration of a size and shape approximately the same as that of a conventional fountain pen including a housing body assembly of elongated generally cylindrical configuration and a separate housing cap structure of elongated generally cylindrical configuration having an elongated clip thereon. The housing cap structure is detachably secured to the housing body assembly in open ended telescopic relation with an opposite end portion thereof preferably by a childproof connection. A medicament cartridge assembly is mounted in a storage position within a forward end of an interior chamber within the housing body assembly and a releasable stressed spring assembly is carried by the housing body assembly adjacent the rearward end thereof. The housing cap structure serves the dual purposes of (1) facilitating the securement of the housing cap structure and body assembly with the user's pocket and (2) alleviating the likelihood of an unwanted release of the releasable stressed spring assembly with a resultant unwanted movement of the hypodermic needle of the cartridge assembly and an unwanted movement of the liquid medicament of the cartridge assembly outwardly of the needle.
