For a long time now students of rhyming slang have been well served by a number of dictionaries. British lexicographers have nonetheless focussed mostly on the English English variety of this slang and have given scant or no attention to other less productive regional varieties in the British Isles. While it has long been known that this form of slang is used in Northern Ireland, lexicographers have not hitherto noticed the vernacular specimens it has yielded there. This article treads new ground by scrutinizing the evidence available for Northern Irish rhyming slang and analysing its distinctive features. The last part of the article unearths a rich subset of the slang lexicon that has largely remained hidden to compilers of dictionaries.