An infusion set adapted to be secured to a skin surface, comprising: a fixed base member (4, 104) including inner guide rails (44, 45), outer guide rails (30, 31, 130, 131) and recesses (73, 74) and connectable to the skin surface; a movable member (3, 103) including first (15, 16) and second projections (19, 20, 119, 120) and having a rigid needle (2, 102) or cannula connected thereto and movable relative to said fixed base member (4, 104), said movable member (3, 103) being movable from a first position in which said needle or cannula is not exposed externally of said fixed base member (4, 104) to a second position in which said needle (2, 102) or cannula is exposed externally of said fixed base member (4, 104), said needle (2, 102) or cannula being disposed at a non-perpendicular angle with respect to said skin surface in said first and second positions via said projections (19, 20, 119, 120) sliding relative to said guide rails (30, 31, 130, 131); a spring member (62, 63, 162, 163) connected to said fixed base member (4, 104) and said movable member (3, 103), said spring member (62, 63, 162, 163) biasing said movable member (3, 103) to move said needle (2, 102) or cannula from said first position to said second position; and a release member (56, 156) retaining said movable member (3, 103) and said spring member (62, 63, 162, 163) in said first position, removal of said release member (56, 156) from said recesses (73, 74) of said fixed base member (4, 104) releasing said spring member (62, 63, 162, 163) and causing movement of said movable member to said second position via said first projections (15, 16) sliding along angled first portions (50, 51) and second portions (52, 53) of said inner guide rails (44, 45) and second projections sliding (19, 20, 119, 120) along said outer guide rails (30, 31, 130, 131), such that the entire movement of the second projections (19, 20) is in a direction substantially parallel to the skin surface, and wherein the second portions (52, 53) of the inner guide rails (44, 45) are substantially parallel to the skin surface, thereby limiting the insertion depth of the needle (2, 102). a fixed base member (4, 104) including inner guide rails (44, 45), outer guide rails (30, 31, 130, 131) and recesses (73, 74) and connectable to the skin surface; a movable member (3, 103) including first (15, 16) and second projections (19, 20, 119, 120) and having a rigid needle (2, 102) or cannula connected thereto and movable relative to said fixed base member (4, 104), said movable member (3, 103) being movable from a first position in which said needle or cannula is not exposed externally of said fixed base member (4, 104) to a second position in which said needle (2, 102) or cannula is exposed externally of said fixed base member (4, 104), said needle (2, 102) or cannula being disposed at a non-perpendicular angle with respect to said skin surface in said first and second positions via said projections (19, 20, 119, 120) sliding relative to said guide rails (30, 31, 130, 131); a spring member (62, 63, 162, 163) connected to said fixed base member (4, 104) and said movable member (3, 103), said spring member (62, 63, 162, 163) biasing said movable member (3, 103) to move said needle (2, 102) or cannula from said first position to said second position; and a release member (56, 156) retaining said movable member (3, 103) and said spring member (62, 63, 162, 163) in said first position, removal of said release member (56, 156) from said recesses (73, 74) of said fixed base member (4, 104) releasing said spring member (62, 63, 162, 163) and causing movement of said movable member to said second position via said first projections (15, 16) sliding along angled first portions (50, 51) and second portions (52, 53) of said inner guide rails (44, 45) and second projections sliding (19, 20, 119, 120) along said outer guide rails (30, 31, 130, 131), such that the entire movement of the second projections (19, 20) is in a direction substantially parallel to the skin surface, and wherein the second portions (52, 53) of the inner guide rails (44, 45) are substantially parallel to the skin surface, thereby limiting the insertion depth of the needle (2, 102).