Segmental distributions of Korean infant-directed speech (IDS) and adult-directed speech (ADS) were compared. Significant differences were found in both consonant and vowel patterns. Korean-speaking mothers using IDS displayed more frequent labial consonantal place and less frequent coronal and glottal place and fricative manner. They showed more use of mid and low central vowels in IDS as well as more use of language-specific Korean phonemes. Mothers produced significantly more fortis and geminate and less lenis consonant phonemes in IDS than in ADS. Findings suggest that Korean mothers speaking to infants in the IDS speech style use sounds that more closely match infant production propensities as well as highlighting perceptually salient properties. IDS may serve to facilitate infant learning of ambient language phonological regularities.