多胺（英语：polyamines，又称聚胺）是一种具有两个或多个主要胺基(－NH2)的有机化合物。

这类的化合物包含一些合成物质，可以做为化学工业中重要的原料，像是乙二胺(H₂N–CH₂–CH₂–NH₂)、1,3-二氨基丙烷(H₂N–(CH₂)₃–NH₂)、六亚甲基二胺(H₂N–(CH₂)₆–NH₂)。它还包括许多物质可以在真核生物、原核生物中发挥重要的作用，例如腐胺(H₂N–(CH₂)₄–NH₂)、尸胺(H₂N–(CH₂)₅–NH₂)、亚精胺(H₂N–(CH₂)₄–NH–(CH₂)₃–NH₂)、精胺(H₂N–(CH₂)₃–NH–(CH₂)₄–NH–(CH₂)₃–NH₂)。

A polyamine is an organic compound having two or more primary amino groups –NH
2 as cations.

Low-molecular-weight linear polyamines perform essential functions in all living cells. Primary examples are putrescine, cadaverine, spermidine, and spermine. In animals, their levels are maintained from both the diet and de novo synthesis, and their decline with age is associated with various pathologies. Polyamine metabolism is regulated by the activity of the enzyme ornithine decarboxylase (ODC). Polyamines are found in high concentrations in the mammalian brain.