A device for automatic injection of a product into an injection site, the injection device comprising: - a container having an open proximal end and a substantially closed distal end and being intended to receive the product, and provided at its distal end with an injection needle providing an outlet port of said container, - a housing (9, 11; 68; 72; 93) intended to receive, at least partially, said container, said container being movable relative to said housing (9, 11; 68; 72; 93) between an initial position, in which said needle is contained within said housing (9, 11; 68; 72; 93), an insertion position, distally spaced relative to said initial position and in which said needle is exposed over a predetermined length, and a final position in which said needle is contained within said housing (9, 11; 68; 72), - retaining means (12, 15; 46, 47; 104, 105, 107), arranged to maintain said container in said insertion position, - deactivating means (20; 49; 99), arranged to release automatically said retaining means and cause said container to move to said final position, - temporizing means (19, 26, 27; 41, 43; 50; 51; 52; 53; 55, 56; 57, 58; 59, 63; 79, 75, 76; 96, 97, 98), arranged to control the release of said retaining means by said deactivating means until substantially all of the product contained within said container has been caused to pass through said outlet port and said injection needle before said container moves to said final position, said device further comprising: - a needle shield coupled with said housing (9, 11; 93) and covering the needle prior to use of said device, and before use, said housing (9, 11; 93) is coupled to a deshielder comprising a cap to which is fixed said needle shield, characterized in that said housing comprises grooves for guiding the translation of said cap when said cap is removed together with the removal of said deshielder in view of using said device, removal of said needle shield being with limited or no rotation of said needle shield, the rotation of the tip of the needle within the rubber forming the needle shield being avoided, and potential coring caused by the tip of the needle rotating in the rubber forming the needle shield being therefore prevented. - a container having an open proximal end and a substantially closed distal end and being intended to receive the product, and provided at its distal end with an injection needle providing an outlet port of said container, - a housing (9, 11; 68; 72; 93) intended to receive, at least partially, said container, said container being movable relative to said housing (9, 11; 68; 72; 93) between an initial position, in which said needle is contained within said housing (9, 11; 68; 72; 93), an insertion position, distally spaced relative to said initial position and in which said needle is exposed over a predetermined length, and a final position in which said needle is contained within said housing (9, 11; 68; 72), - retaining means (12, 15; 46, 47; 104, 105, 107), arranged to maintain said container in said insertion position, - deactivating means (20; 49; 99), arranged to release automatically said retaining means and cause said container to move to said final position, - temporizing means (19, 26, 27; 41, 43; 50; 51; 52; 53; 55, 56; 57, 58; 59, 63; 79, 75, 76; 96, 97, 98), arranged to control the release of said retaining means by said deactivating means until substantially all of the product contained within said container has been caused to pass through said outlet port and said injection needle before said container moves to said final position, said device further comprising: - a needle shield coupled with said housing (9, 11; 93) and covering the needle prior to use of said device,