A buckle for use with a safety harness includes a plurality of slots each for receiving an end of a harness belt section, each slot having associated therewith a retainer which is moveable into and out of engagement with an abutment surface defined by the end of a belt section, first bias elements normally to urge the retainers to move to a position at which they each engage with an abutment surface of the end of a belt section following insertion into a slot, at least one of the retainers having associated therewith a lever which is pivotable against the action of the first bias elements to move the retainer to a release position at which it is free from engagement with the abutment surface, and an actuation member operable to act on the or each lever whereby the or each lever moves a retainer to the release position.