This study presents one of the most influential grammatical models in the literature of code-switching, i.e. Myers-Scotton``s matrix language-frame model (MLF model). The study also tests the universal validity of the model, on Korean-Swedish single word code-switching. The data consist of tape recordings of spontaneous adult, child and family conversations among Koreans in Sweden. Linguistic analysis shows that many single words contain the function words (or morphemes) and the morpheme orders from the original language. From these single words we can reasonably infer that the universal character of the MLF model is unreliable, at least judged by the Korean-Swedish material. In order to cover these cases, some modifications of the model are necessary.