Portable drug delivery device having an encapsulated needle

The present invention relates to medical devices which are adapted for application to a skin surface of a user and comprise a transcutaneous device which is supplied in a sterile condition. Thus, a medical device is provided, comprising a mounting surface adapted for application to the skin of a subject, a first portion having a first end adapted to penetrate the skin of the subject, and a second portion in fluid communication with the first portion and having a second end. The device further comprises enclosure means being transformable from an initial configuration encapsulating the first and second portions in an initial aseptic state, to a second configuration in which the ends of the first and second portions are allowed to communicate with the exterior through the enclosure means, wherein the enclosure means does not enclose the mounting surface.