South Kyungsang Korean is spoken in the southeastern part of Korea. The critical problems in analyzing this language are the substantial inconsistency among authors concerning tonal descriptions, and the typologically unusual tone alternation patterns, which have consequently led to vague tonal contrasts and conflicting data. Given that the majority of earlier studies on this language have been based on transcription data, there is limited physical evidence concerning these issues. This research therefore presents the phonetic realization of tonal contrasts, based on F0 production and perception experiments. It was found that there are three distinct tone classes in monosyllabic roots, and they are different in F0 height, syllable duration, and the timing of F0 peak and fall both in unsuffixed words and in suffixed words. It has been suggested, based on this acoustic evidence, that South Kyungsang Korean has three different tone contrasts in monosyllabic roots, e.g., M, H, and R, and that the different tone alternation patterns of these three tone classes in suffixed words might be the reflection of the phonetic implementation of each tone class. This work provides not only new basic facts of South Kyungsang Korean tonology, but also another way of understanding tone targets and tone alternation patterns. While clarifying the complications in a particular language, the findings in this work also contribute to debated topics of modern intonational research, concerning such as phonological and linguistic units in the F0 continuum, the temporal alignment of F0 features with segmental strings, and perception of tonal contrasts.