Abstract: An adaptor for a bayonet type, multi-pin cable connector including male and female terminal parts, the male part having radial bayonet pins engageable with bayonet slots of a coupling collar rotatably mounted on the female part. The adaptor includes a ring surrounding and secured to the coupling collar and provided with a radially protruding finger piece to facilitate collar rotation from unlocking to locking position. The finger piece extends through a slot made in a body which surrounds and is fixed to the female part. This slot provides abutments at its ends to prevent rotation of the finger piece, ring and coupling collar past the unlocking and locking positions of the coupling collar. The body has a flat guiding surface engageable with a flat guiding surface associated with the male part to facilitate bringing the two parts in coupling position.