<jats:title>Abstract</jats:title><jats:p>Borrowing affixes may be rare compared to lexical borrowing, but it is not random. The current study describes regular patterns of affix borrowing in a database containing 649 borrowed affixes, challenging a number of previous claims about relative borrowability, in particular regarding inflectional categories. It is shown that borrowing affixes of all major nominal and verbal inflectional categories, including case markers and argument indexes, is well attested. Borrowing case markers, for instance, appears to be just as common as borrowing plural markers. By factoring in the “availability” for borrowing (i.e. whether a potential donor language has a relevant affix), it can be shown that nominal categories are far more frequently borrowed than verbal categories. Additionally, it is shown that sets of borrowed affixes often consist of interrelated sets of forms, e.g. forming paradigms, rather than being isolated forms from different morphosyntactic systems, in particular for the more tightly integrated inflectional subsystems. The frequency and systematicity by which inflectional affixes are borrowed calls for a reconsideration of the role of inflection in models of language contact.</jats:p>