This study focuses on the resource allocation of multicast services in distributed antenna systems (DAS). Firstly, the capacity limitation of conventional multicast transmission is analysed in DAS. Then a resource allocation algorithm is proposed for multicast services to improve the system throughput of DAS with quality of service (QoS) guarantees. A low-complexity suboptimal algorithm is also presented, which includes three steps: conservative allocation, greedy step and iterative enhancement. Simulation results show that the proposed algorithms significantly outperform conventional multicast transmission in throughput while guaranteeing the minimum data rates of all users as well. Moreover, the performance of the suboptimal algorithm is close to that of the optimal one and the throughput loss is negligible. Meanwhile, it is also shown that the proposed algorithms can exceed the upper bound of conventional multicast scheme when the user number is larger, which indicates the proposed algorithms can overcome the capacity limitation of conventional multicast transmission in DAS.