Executive Summary Hospitals provide services to all kinds of people; whether they are rich or poor, educated or unlettered. Different patients will have different levels of expectations on hospitals' services. When hospitals provide services that are lower than patient's expectations, patients may recognize that the hospital is providing poor services. Thus it may induce patients to raise complaints. Different types of patients will have different complaint responses, such as doing nothing, express their dissatisfaction to families and friends, directly raise complaints to the hospital and take serious action like express their grievances to the media, or even sue the hospital. Those complaint responses would affect a certain degree of impact on the hospital brand image. Some conditions like process charateristic (the interaction between service staff and service user within that environment during the service performance), personal background and negative emotions may also cause complaint behavior to happen. Currently, Macau is served by one public and two private hospitals. This study will mainly investigate those who have used the services in the public Conde de São Januário Hospital (CHCSJ) or the private hospital, Kiang Wu Hospital (KWH). CHCSJ and KWH is providing the main hospital service in Macau, when patient experiences unsatisfactory hospital services, some serious complain actions may start, in order to avoid the serious complain action, this study aims to understand which hospital services are most concerned by Macau hospital users and determine the statistical significant of influence factors (e.g. hospital service failures, negative emotions, personal background and process characteristics) that trigger patients to complain about hospital services in Macau. A questionnaire research method is carried out with a sample size of 206. The result show that there is one hospital service failures of slow medical service that has a significant positive impact on patient's anger emotion, the anger emotion has a significant impact on patient raising complaint with the hospital. In addition, the other factors include household income earners at $4,000 to $8,999 and process characteristics about staff's competence and availability of the physician, these factors have also had significant impact on patient raising complaints with the hospital. The finding of this study can help hospitals to understand that the speed of medical service got the most concerns from patients. The speed of the medical service, hospital staff competence and the availability of the physician are the important factors that would impact the income earners at $4,000 to $8,999 raising complaints with the hospital. This finding can help managers to understand the most important needs of patients. Through the finding of this study, managers can establish specific improvement schemes and diminish the power of influential factors impacting the hospital's image.