All records of Leach’s Petrel off Machrihanish, south-west Kintyre in Aug-Nov are given for the ten years 1989-1998. For western Scotland, examples of major occurrences of this species (>40 birds/day) are listed, together with records of exceptional numbers (>I 00 birds/day) of Storm Petrel. The meteorological conditions and the activity of other seabirds that accompanied major occurrences of Leach’s Petrel at Machrihanish are described. The extreme weather conditions that favoirr inshore occirrrence of this oceanic species seem not to have a similar effect on the more numerous Storm Petrel, since simiiltaneoirs sightings of the two species are infrequent. The flight behavioiir of each species in severe gale conditions is described.