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Pinault's law is a Proto-Indo-European (PIE) phonological rule named after the French Indo-Europeanist Georges-Jean Pinault who discovered it.

According to this rule, PIE laryngeals disappear between an underlying non-syllabic consonant (i.e. an obstruent or sonorant) and *y. Examples can be seen in the formation of imperfective verbs by appending *-yeti to the stem. Compare:

• PIE root *werh₁- 'to say' → imperfective *wéryeti 'to be saying' (cf. Ancient Greek εἴρω 'to tell')
• PIE root *h₂erh₃- 'to plow' → imperfective *h₂éryeti 'to be plowing' (cf. Old Irish airid 'to be plowing')
• PIE root *snéh₁- 'to spin' → imperfective *snéh₁yeti 'to be spinning' (cf. Old Irish sniïd). Here the laryngeal */h₁/ is not deleted since it is preceded by a vowel.