The project managers' major concern is to complete project cost effectively and timely. But, in real life, the project completion time and cost may vary significantly as an effect of uncertainty such as weather, political and social disturbances, inflation, site congestion, human factors, productivity level, etc. Minimisation of project cost directly depends on proper utilisation of resources. Therefore, a GA-based fuzzy optimal model is proposed in this study incorporating multi-objective approach (MAWA) for project time-cost trade-off. In this study, fuzzy set theory is applied to model the managers' behaviour in predicting time and resources of activities and α-cut method in fuzzy logic theory is used as a measure of accepted risk level. In addition, the activities of project are crashed and penalty is induced for delay to make such problem realistic. The proposed model leads the managers to choose the Pareto optimal time-cost solutions under different risk levels as well as their associated degree of belief in a more flexible and realistic manner. Finally, this proposed model is used to solve a real problem. Copyright © 2013 Inderscience Enterprises Ltd.