The article examines the history of the trade in Polish slaves and captives in the Tatar and Ottoman Crimea in the seventeenth century on the basis of hitherto unknown archival evidence and rare printed sources. After the capture an average Polish slave of simple origin was transported to the Crimea, where he had been sold on the local slave markets. Unless he had some special qualifications, a slave usually had to fulfil agricultural duties and do heavy manual work. The slaves usually had some limited free time and could attend Catholic services in the churches of the Crimea's large urban centres. Rich Polish captives were treated in accordance with their high social status and were ransomed for a considerable redemption fee. Important role in ransoming such rich captives was played by Jewish, Tatar and Armenian merchants.