The Pacific abalone Haliotis discus hannai is a commercially important marine mollusk.To develop a rapid,economically efficient and robust approach for genetic studies in this species,twelve microsatellites were used to optimize four multiplex PCRs for the H.discus hannai,and the results obtained indicate the usefulness of the four multiplexed microsatellite systems in parentage assignment.We evaluated and validated these multiplex PCRs in 12 full-sib families.The average polymorphism information content(PIC)was 0.82.Inheritance analyses in the 144 tests showed that 4.9% microsatellite loci deviated from Mendelian ratios.The frequency of null alleles was estimated at 10.6% of all the alleles segregating based on a within-family analysis of Mendelian segregation patterns.Simulations and parentage analysis showed that with the most informative multiplex set 4,the assignment success could be 86% and 90% respectively,and 100% of the offspring were correctly allocated to their parents when two or more multiplex PCRs were used.Our results show that four multiplex PCR panels of microsatellites are possible and can be used for rapid and highly efficient parentage assignment in the Pacific abalone.