Mentir Conjugation: All Tenses of the French Verb “mentir”
Written by Camille Laurent, Lead French Curriculum Editor · Reviewed August 2026
Mentir means “to lie” in the sense of saying something untrue. It is a third-group verb that drops a consonant in the present singular (je mens, il ment) and takes the preposition à before the person being lied to.
Mentir comes up as soon as you start telling stories about people: tu me mens, il a menti, elle mentait tout le temps. It also anchors a small family you will meet constantly — sentir, partir, sortir, dormir and servir all conjugate on the same model, so the effort you spend here pays off five times over. The two things to get right are the shrinking stem in the singular and the à that follows it.
The present tense has two stems. In the singular the t of the stem disappears: je mens, tu mens, il ment. In the plural it comes back: nous mentons, vous mentez, ils mentent. Everything else is built on that full stem — the imparfait (je mentais), the subjunctive (que je mente), the present participle (mentant). The future and conditional use the whole infinitive: je mentirai, je mentirais. The past participle is menti, it takes avoir, and it never agrees, because mentir has no direct object: what follows is always à quelqu'un.
Mentir in context
Présent
Je sais qu'il ment, mais je ne dis rien. I know he's lying, but I'm not saying anything.
Imparfait
Elle mentait sur son âge depuis des années. She had been lying about her age for years.
Passé composé
Tu as menti à tes parents pour couvrir ton frère. You lied to your parents to cover for your brother.
Futur simple
Si on lui demande, il mentira encore. If anyone asks him, he'll lie again.
Subjonctif présent
Je ne veux pas que tu me mentes sur ce point. I don't want you lying to me about this.
Common mistakes with mentir
Keeping the t in the singular
✗ Je ment rarement.
✓ Je mens rarement. — I rarely lie.
The singular forms are je mens, tu mens, il ment: the -s belongs to je and tu, and the -t to the third person. Writing je ment mixes the two. The stem's own t only reappears in the plural, in nous mentons and ils mentent.
Treating the person lied to as a direct object
✗ Il a menti sa femme.
✓ Il a menti à sa femme. — He lied to his wife.
English lets you say “he lied to her” with a bare object pronoun, and learners drop the preposition in French. Mentir is intransitive and needs à: mentir à quelqu'un, and with a pronoun il lui a menti, not il l'a menti. What you lie about takes sur: mentir sur son âge.
Borrowing the stem of mener
✗ Nous menons rarement à nos amis.
✓ Nous mentons rarement à nos amis. — We rarely lie to our friends.
Nous menons is a real French form, but it belongs to mener, “to lead”. Mentir keeps its t whenever the ending is pronounced: nous mentons, vous mentez, ils mentent. Dropping it turns the sentence into a different verb rather than into a mistake you can hear.
Expressions with mentir
mentir comme un arracheur de dents
to lie through your teeth
mentir effrontément
to lie brazenly
se mentir à soi-même
to lie to yourself
un mensonge
a lie
Frequently asked questions
Is mentir a regular verb?
No, it belongs to the third group. Its endings in the present are -s, -s, -t, -ons, -ez, -ent rather than the -ir endings of finir, and the stem loses its t in the singular: je mens, il ment. The good news is that sentir, partir, sortir, dormir and servir all follow the same model.
What is the past participle of mentir?
Menti, used with avoir: j'ai menti, ils ont menti. It never changes form, because mentir cannot take a direct object — the person you lie to is introduced by à. So elle a menti stays menti even in the feminine, and there is no agreement to worry about.
Do you say mentir à or mentir de?
À, for the person: mentir à quelqu'un, il m'a menti, elle a menti à son patron. For the subject of the lie, use sur: mentir sur son âge, sur ses diplômes. If you want the thing said, use a clause instead: il a dit qu'il était malade.
What is the difference between mentir and tromper?
Mentir is about words: you say something you know is untrue. Tromper is about deceiving someone by any means, and in the context of a relationship tromper quelqu'un specifically means to be unfaithful. Someone can mislead you without lying outright, which is where tromper or induire en erreur fits.
How do you pronounce je mens and il ment?
Identically. Both are one syllable with a nasal vowel and a silent final consonant, roughly “mahn”. The plural is where the sound changes: mentons and mentent bring the t back audibly. So in speech, only the pronoun tells you which singular form you are hearing.