This article is about the productivity of pluralization rules in Mosuli Arabic ( a dialect spoken in Northern Iraq). It particularly examines adding the plural suffixes in Mosuli Arabic ( the sound- masculine , the sound-feminine , and the broken plural suffixes) to a corpus of English loanwords that are in current use in this dialect. The study comes to the conclusion that the sound- feminine suffix is more commonly added to loanwords irrespective of their gender and thus this rule is the most productive rule among the three pluralization rules. Some structural and morphological constraints that restrict the application of the other two rules have been identified.