This master thesis deals with the theory of Lexical-Functional Grammar (LFG) and the phenomena of phonetic non-realisation in Japanese and Korean. Radical pro-drop languages, such as those just mentioned, allow linguistic elements in a sentence to be unpronounced without losing grammaticality. The phenomena of phonetic non-realisation include pro-drop, ellipsis, and null arguments. This thesis focuses on three dimensions of LFG to describe these phenomena in Japanese and Korean, namely the constituent-, functional- and argument-structure (c-, f- and a-structure for short). Firstly, the theory-building terms of LFG, namely Lexical, Functional and Grammar, are introduced and explained. Secondly, detailed information on the three structural levels is provided. Thirdly, the correspondence between these dimensions is illustrated using a Japanese and Korean example. Fourthly, the terms pro-drop, ellipsis and null argument are distinguished from each other and their state of research regarding the Japanese and Korean language is presented. Lastly, the phenomena of phonetic non-realisation of the two languages are examined within the framework of LFG. The thesis uses descriptive and comparative methods to analyse the differences and similarities between Japanese and Korean concerning their c-, f- and a-structure. The analysis shows that, due to their structural similarity and agglutinative nature, the two languages are also similar in terms of their behaviour regarding pro-drop, ellipsis, and null arguments. Japanese and Korean both allow the subject, direct and indirect object argument to be omitted if the context is given by the preceding discourse. It is possible that the linguistic entities are absent in the c-structure but information on them is present in the f- and a-structure., Simone Fuchs, BA, in englischer Sprache, Masterarbeit Universität Innsbruck 2023