A releasable medical device connector comprises a connector fitting with a spin nut which connects to an adaptor. The connector fitting has at least one radially extending member with a variable radius cross section. The spin nut is disposed upon the connector fitting proximal of the radially extending member and is both axially slidable and rotatable upon the elongated body of the connector fitting. A screw thread within a proximal portion of the spin nut is used to secure the tapering portion of the connector fitting to an external thread disposed upon the adaptor. To release the connector, the spin nut is unscrewed from the adaptor and slid so that a distal receptacle of the spin nut engages the radially extending member of the connector fitting. With the spin nut and connector fitting engaged, the medical line can be released from the adaptor by twisting and pulling upon the spin nut. The radially extending member of the connector fitting may also be used to secure the medical line to a retainer comprising one or more slots.