Abstract Repetition avoidance, one characteristic of human cognition, affects human behaviour to a great extent. The present study aims to extend the understanding of repetition avoidance to sentence comprehension in Korean, a language typologically different from the major languages that have been investigated for this issue. I measured the degree of acceptability and reaction times for two types of multiple postposition constructions in Korean, each of which has two grammatical patterns involving postposition alternations (dative-accusative and accusative-accusative for the dative construction; topic-nominative and nominative-nominative for the double subject construction). Results showed that the patterns involving repetition of postpositions were dispreferred over those without the repetition, and that by-pattern reaction times within each construction type were modulated by the postposition types repeated in the patterns. The findings of this study support the role of repetition avoidance for sentence comprehension in Korean (and perhaps beyond), and suggest an interplay between a domain-general factor (repetition avoidance) and language-specific knowledge (postpositions).