Abstract: An electronic vapor provision system includes a first unit comprising a battery and a second unit comprising a heater and a nicotine source for producing nicotine vapor when heated. The first unit and the second unit comprise a bayonet fitting for providing a mechanical and electrical connection therebetween. The system has a longitudinal axis, and the bayonet fitting is configured such that the first and second units are connected by relative movement thereof along the longitudinal axis to a first engagement position, and relative rotation of the first and second units about the longitudinal axis from the first engagement position to a final engagement position that prevents both (i) relative movement of the first and second units along the longitudinal axis, and (ii) relative rotation of the first and second units further away from the first engagement position.