Macau experienced unprecedentedly high demand of consultancy services for concurrent constructions of hotel resort and infrastructure projects as a result of rapid growth of construction in the last decade after the liberalization of the Gaming industry. Service quality of construction consultants is important to Macau’s economic growth and for the development of the construction industry. The quality of construction projects will be jeopardized and limited construction consultants will be held up for project delay or rework if consultants are under-achieving. Adopting the Gap Analysis approach from the research by Low and Yeoh (2004) and using thirty assessment scales expanded from Hoxley’s (2000) original 26-item scales in research about the construction professional service quality in the UK, this study seeks to examine the perceived importance in scales and satisfactions and identify the gaps between clients’ expectations of consultants’ services quality and consultants’ perceptions of clients’ expectations. The 170 survey responses, 90 from respondents working as client of integrated resort hotel projects developed by six gaming concessionaires in Macau Cotai area and 80 from respondents working as construction consultants engaged by them, was analyzed. The perceptions of the most important and the least important scales by clients and consultants is very close. Nine scales are identical within ten most important scales perceived by clients and consultants, where the first four most importance scales (“staff's competence in solving clients' problems”, “staff's knowledge on solving problems”, “ability to understand clients' problems”, and “securing clients' best interest at heart”) are identical and the first two least important scales (“staff's tidy appearance” and “having similar views with clients about projects”) are the same. Thirty scales important to service quality were condensed into five principles components (time, 2 communication, knowledge, people and design), and the ‘time’, ‘knowledge’ and ‘communication’ related factors are perceived as the core value of both clients and consultants. Clients’ weighted mean scores were subtracted from consultants’ for gap scores. The results revealed that discrepancies exist between clients’ perceptions and consultants’ perceptions of clients’ perceptions in importance for all thirty scales. This finding appears to suggest that as long as consultants’ perceptions of clients expectations is close to clients’ expectations, consultants will naturally devote sufficient attention and efforts to those scales critical to their service quality and as a result clients will be satisfied with their consultants. To improve construction consultancy service quality in Macau, clients and consultants are recommended to pay attention to the ten most important scales perceived by clients, devote sufficient efforts, invest in training program for staffs and work in close collaboration together for implementing improvement plan. In implementation, clear measurable objectives are to be set and focus given on quantified targets, milestones and performance indicators to deliver improvement in a continuing basis. The traditional competitive tendering shall be replaced with long term relationships based on mutual interests and sustainable improvement. Consultants shall address to the most important factors of “time”, “communication” and “knowledge” that are the core value of the clients and focus on those factors that have negative gap scores. And, they shall improve the service quality as to develop a competitive advantage specific to the professional service that cannot be easily imitated by competitor and hence can differentiate themselves by completing a project in a shorter time and lesser cost but to the highest clients’ satisfaction. Finally, the new Five-Factor Construction Consultancy Service Quality Assessment Scales derived can be used to measure and predict construction professional service quality in Macau.