The present study aims at establishing grammatical constraints on the borrowing of nouns (Ns) and verbs (Vs) in Urdu and English by adopting Noam Chomsky's Methodological Naturalism within the field of generative grammar as the theoretical framework of the study. For this purpose, the corpus of Pure Urdu and Pure English sentences from textbooks and the Oxford Dictionary of English was used in this study. The data were analyzed in the light of Minimalist Program, and the findings of the study reveal that there are certain grammatical constraints on the borrowing of Vs in Urdu from Persian, Arabic, Sanskrit, and Hindi as compared with English. It is observed that whenever Urdu borrows Vs from other languages such as Arabic, Persian, and Sanskrit, it adds its little v with the fossil form of borrowed verbs in order to retain the grammaticality of the sentence while in English Vs borrowed from Latin, old English is said to be used in their fossil form and can be used with the inflection of the English and has no effect on the grammaticality of the sentence. The reason observed is the drop v phenomenon. Urdu does not drop its little v due to which whenever it borrows Vs it adds its little v along with root form of borrowed Vs otherwise the resulting structure is considered as ungrammatical. If we talk about the borrowed Ns, there are no grammatical constraints on their borrowing because they can inflect with inflectional morphology of Urdu and English language.