The grammar of the Persian language is similar to that of many other Indo-European languages. Persian became a more analytic language around the time of Middle Persian, with fewer cases and discarding grammatical gender. The innovations remain in Modern Persian, which is one of the few Indo-European languages to lack grammatical gender, even in pronouns.

While Persian has a standard subject-object-verb (SOV) word order, it is not strongly left-branching. It uses prepositions, not postpositions, and is mainly a head-initial language. Persian is a pro-drop language since its verbs have unambiguous personal suffixes and so the use of pronouns is optional. Thus, the subject mark often appears as a suffix at the very end of the sentence.

The main clause precedes a subordinate clause, often using the familiar Indo-European subordinator ke ("which").

The interrogative particle âyâ (آیا), which asks a yes–no question, appears in written Persian at the beginning of a sentence. Grammatical modifiers, such as adjectives, normally follow the nouns that they modify with the suffix ezâfe (اضافه), but occasionally precede nouns. Persian is one of the few SOV languages to use prepositions. The only case marker in the written language, râ (را) (replaced in the spoken language by ـ رو ro or ـو o), follows a definite direct object noun phrase.

Normal sentences are subject-prepositional phrase-object-verb. If the object is specific, the order is (S) (O + râ) (PP) V. However, Persian has a relatively free word order, which is often called scrambling, since its parts of speech are generally unambiguous, and prepositions and the accusative marker help to disambiguate the case of a given noun phrase. That characteristic allows Persian to have a high degree of flexibility for versification and rhyming.

In the literary language, no definite article ("the") is used; rather, it is implied by the absence of the indefinite article ("a, an"). However, in the spoken language, the stressed suffix ـه -e or -a is often used as a definite article; -e is used mostly in urban areas and in newer dialects, and -a is used mostly in rural areas and in older dialects. Persian consonants and vowels have changed throughout history.

For plural nouns, the definite plural marker ـ‌ها -hâ functions as both the plural marker and the definite article.

The indefinite article in both spoken and literary Persian is the same as the word for 1, یک yek, which is often shortened to یه ye.