The Not Too Overly Possessive Pronouns
The possessive pronouns are, as their name implies, selfish, because they insist on doing the work of the genitive form of the personal pronouns. These pronouns are adjectival since they occur in attributive position before the noun they modify and agree in case, number, and gender with the noun. There is one corresponding to each of the 'persons' of personal pronouns. Here is a list of their citation (nominative singular masculine) forms.
The Possessive Pronouns Person Singular Plural 1st мой my наш our 2nd твой your ваш yalls 3rd её her, its
его his, its
The good news is this: the first- and second-person possessive pronouns follow the general rule of pronouns stated at the top of the page. That is, these possessive pronouns have noun endings in the nominative and accusative and adjective endings everywhere else, so you already know their endings. The even better news is that the 3rd person possessive pronouns, её, его and их are indeclinabletheir form never changes! (Russians will do anything to keep their language simple.)
So, you have no further memorization if you just keep in mind two spelling rules:  the й + vowel spelling rule for forms like "my (neuter)" and "your (feminine)", the 7-consonant rule for forms like "our (plural)" and the 5-consonant rule for those like "your (plural)". In the table below, the 1st person pronouns are given in the Masculine - Neuter, while the 2nd person pronouns are in the Feminine.
Possessive Pronoun Declensions:
1st & 2nd Persons
Singular Case 1stSg 2ndSg 1stPl 2ndPl Nominative мой, мое твоя наш, наше ваша Accusative мой, мое твою Nom/Gen вашу Genitive моего твоей нашего вашей Dative моему твоей нашему вашей Prepositional моём твоей нашем вашей Instrumental моим твоей нашим вашей Plural Nominative мои твои наши ваши Accusative Nom/Gen Nom/Gen Nom/Gen Nom/Gen Genitive моих твоих наших ваших Dative моим твоим нашим вашим Prepositional моих твоих наших ваших Instrumental моими твоими нашими вашими
Don't be intimidated by the size of the possessive pronoun declension table. Take a close look and you will see that in the nominative and accusative of both declensions (which I've darkened to help you spot them), the ending is the same as the nouns of the corresponding gender and that all other endings are the same as the corresponding adjective endings. You already know them! Congratulations on a job well done!
The only catch to the possessive pronouns is found in the interrogative possessive pronoun, the one that means "whose" чей, чья, чьё, чьи. You have to remember that, except in the masculine singular, чей, there is a soft sign before the endings. Otherwise, this possessive pronoun declines like all others.
Of whose table?
На чьём письме?
On whose letter?
Oh, by the way. . .the possessive reflexive pronoun свой, своё, своя; свои is declined the same as мой and твой It is used when the referent of the possessive is identical with that of the subject, e.g. Я взял свою книгу "I took my (own) book".
Test Your Knowledge of Possessional Pronouns
Here are a few exercises to test your grasp of possessiveness in Russian. Choose the correct case form of the pronoun listed to the right of the sentence and type it into the appropriate space. (Be sure to distinguish e and ё).