A medical device comprising: a connector housing and a frontal attachment to the connector housing, the connector housing and frontal attachment being cooperatively engaged in closely spaced sliding relation to each other along at least one sliding interface; a needle retraction assembly seated inside the frontal attachment, the needle retraction assembly comprising a rearwardly biased needle holder; a retractable needle projecting forwardly from the frontal attachment; and a fluid seal disposed between the connector housing and the frontal attachment; the connector housing further comprising at least a body portion of an associated medical apparatus and a fluid pathway communicating with the needle holder through the fluid seal, and a needle retraction chamber having a needle retraction cavity that is spaced apart laterally from the fluid pathway characterized in that the connector housing further comprises a forwardly facing surface and rails (64, 66), a first opening communicating with a rearwardly facing connector, and a second opening into the needle retraction cavity, wherein connector has luer locking tabs provided near rear end for use in attaching connector to the associated medical apparatus and wherein the associated medical apparatus is a syringe having a generally cylindrical barrel with a forwardly facing luer connector and a plunger; the frontal attachment further comprises base and forwardly projecting needle support, wherein base has a rearwardly facing surface and a plurality of cooperatively engageable rails (91, 93) that can be snapped into sliding engagement with rails (64, 66) of connector housing along the at least one sliding interface, and wherein the at least one sliding interface is substantially transverse to a longitudinal axis through the retractable needle. a connector housing and a frontal attachment to the connector housing, the connector housing and frontal attachment being cooperatively engaged in closely spaced sliding relation to each other along at least one sliding interface; a needle retraction assembly seated inside the frontal attachment, the needle retraction assembly comprising a rearwardly biased needle holder; a retractable needle projecting forwardly from the frontal attachment; and a fluid seal disposed between the connector housing and the frontal attachment; the connector housing further comprising at least a body portion of an associated medical apparatus and a fluid pathway communicating with the needle holder through the fluid seal, and a needle retraction chamber having a needle retraction cavity that is spaced apart laterally from the fluid pathway characterized in that the connector housing further comprises a forwardly facing surface and rails (64, 66), a first opening communicating with a rearwardly facing connector, and a second opening into the needle retraction cavity, wherein connector has luer locking tabs provided near rear end for use in attaching connector to the associated medical apparatus and wherein the associated medical apparatus is a syringe having a generally cylindrical barrel with a forwardly facing luer connector and a plunger; the frontal attachment further comprises base and forwardly projecting needle support, wherein base has a rearwardly facing surface and a plurality of cooperatively engageable rails (91, 93) that can be snapped into sliding engagement with rails (64, 66) of connector housing along the at least one sliding interface, and wherein the at least one sliding interface is substantially transverse to a longitudinal axis through the retractable needle.