The present thesis is a study of adaptation in commercial advertisement translation (CAT) conducted from a functional perspective. Although viewed as one of the most controversial translation strategies in history, adaptation is a translation strategy frequently used in present day CAT. Besides, many studies have been carried out on this topic in recent years, but very few of them are carried out from the functional perspective. It is under this background that this study sets out to explore the area of CAT. This study attempts to provide a systematic description and analysis of adaptation within the area of CAT, followed by a discussion to explore the main reasons and factors behind the adaptive methods. It is hoped that the results of the research will provide some useful reference to translation teaching and translator training. Reiss's text typology and Nord's theoretical model of text classification, especially the subdivision of the appellative text, namely, direct appellative text, indirect appellative text and poetic appellative text, are applied as major theoretical tools in the study. Other theories concerning functional approaches, such as Nord's "function plus loyalty" is also reviewed and applied in our discussion. The data are genuine commercial advertisements collected from the downtown commercial areas and tourist service centers in Hong Kong and Macao in 2005 and 2006. In this thesis, six commercial advertisements and their translations are analyzed. Further study is done through the comparison of the source text, target text colleted from the real world and the reference translation done by the present researcher. The results of the study indicate that various adaptive methods are employed in CAT, such as interpretation, amplification, omission, conversion ,affirmation, negation, separation/combination, as well as restructuring. It is also found out that adaptive methods are widely used in all kinds of commercial advertisement texts, which are categorized by Nord as direct appellative, indirect appellative and poetic appellative texts. The two possible reasons for adopting the strategy of adaptation in CAT are the generic convention and the acceptability of texts to the readership. This thesis is divided into five chapters. Chapter I introduces the background and objectives of the study, Chapter Il reviews relevant literature concerning equivalence, adaptation and functional theories of translation, Chapter Ill analyzes the collected data. Chapter IV discusses the findings of the research and explores possible reasons for the use of adaptation in CAT, Chapter Y summarizes the main points and points out limitations of the study. Keywords: adaptation, commercial advertisement translation (CAT), equivalence, function, text typology