This research examines the effects of morpheme boundaries on the timing of fundamental frequency (f0) peaks and demonstrates that phonetic realization is influenced by morphological structure. It reports the timing of f0 peak and peak plateau in monomorphemic HH (high, high tone) and HL (high, low tone) as well as bimorphemic H+H and H+L in South Kyungsang Korean, spoken in the southeastern part of Korea. The results show that f0 peak came significantly later in bimorphemic H+H than in monomorphemic HH and peak plateau was significantly longer for monomorphemic HH than for bimorphemic H+H. It suggests that f0 peak plateau is implemented more stably within a single lexical item than across a boundary between lexical items. However, a significant morpheme effect was not found in monomorphemic HL and bimorphemic H+L. In accounting for these asymmetrical results, several hypotheses were discussed including speakers hyperspeech effort [H&H theory, Lindblom (1990)], intrinsic vowel height on f0 [Hombert et al. (1979)], and f0 peak delay effect on phonologically suggested H tone spreading [de Jong and McDonough (1993)]. It is proposed that the bimorphemic H+H in this language is the phonetic image of the f0 peak delay effect of high tone.