The breeding behaviour of female natterjack toads Bufo calamita at an isolated population in Hampshire, UK was investigated over a period of four years. In all four breeding seasons some (2-10) females laid two clutches of spawn, the first direct evidence of double-spawning by natterjacks in the wild. The mean period between clutch depositions was 63 days and the first clutches contained about twice as many eggs as the second ones. Double-clutching females were significantly larger than single-clutching ones, but not significantly larger than early spawners which were found in amplexus again late in the season but which did not spawn a second time. Late spawn, including second clutches, failed to produce toadlets in any of the four years of study.