Case-based reasonging (CBR) is an emerging methodology in ArtificialIntelligence (AI). A case is a situation, episode, etc. remembered (stored) by acomputer, and the attempt to reuse it is the subject of case-based reasoning[3,4,5]. CBR reasons by means of past cases stored in its case library, byretrieving similar cases in the past matched against the user input problemsituation, and then using pre-defined adaptation knowledge to reuse the retrievedcase to fit current situation. This paper presents the basic concepts of CBR, itsreasoning cycle, the major classes of adaptation methods used in CBR and abrief introduction of case-based adaptation (CBA). In addition, severalapplications of CBR in Macau are presented in the paper.