“Do not go gentle into that good night” is a villanelle. The villanelle is a strict poem form that consists of 19 lines—five tercets (or three-line stanzas) and one quatrain (or four-line stanza). Villanelles also feature a specific pattern of repetition: The first and third lines repeat themselves throughout the poem as dual refrain. This poem’s refrains are “Do not go gentle into that good night” (Line 1) and “Rage, rage against the dying of the light” (Line 3). Line 1 repeats itself as Line 6, 12, and 18. Line 3 repeats itself as Line 9, 15, and 19.

The poem’s refrain lines rhyme with each other, while the rest of the poem’s lines use their own repeating rhyme. The poem’s rhyme scheme is ABA ABA ABA ABA ABA ABAA.

Thomas uses frequent sound devices, particularly relying on consonance and assonance. Consonance is the repetition of consonant sounds that does not specifically occur at the beginning of words (unlike alliteration). Here, both refrains use the consonance of G sounds.