The present study reports results of an investigation into Korean durational patterns with respect to syllable structure and syllable boundary. The main questions raised in this study were (1) whether different preceding syllable structures contribute to the durational patterns of the following segmental durations: closure duration, voice onset timing (VOT), and vowel duration; and, if so, (2) how they are realized, especially over syllable boundaries determined by Korean orthography. Thirty-six two-syllable nonsense words varying in syllable structure were analyzed. For the durational pattern of internal elements of syllables over syllable boundary, the initial consonants of the second syllable were differentiated into lax, tensed, and aspirated stops. Results indicate that initial consonant duration showed no significant difference regardless of syllable structure. Initial vowel duration, however, reflected temporal compensation depending on the syllable structure. In addition, the effect of preceding syllable structure was reflected only on the closure duration, not on the VOT nor on the vowel durations of following syllables. These findings imply that temporal compensation tends to occur across segments over syllable boundaries, suggesting the importance of syllable boundary in durational patterns in Seoul Korean. The relevance of orthography to syllable boundary is also discussed.