Abstract In this work, an experimental investigation of the high velocity impact resistance of syntactic foam core composite sandwich panel has been undertaken. The syntactic foams filled with ceramic microballoons of three different sizes and three different volume fractions. Also, to enhance the matrix strength of the foam core, some specimens reinforced with nano particles. The high velocity impact tests have been carried out using a light gas-gun and a 10 mm blunt-head steel projectile and the ballistic limit was measured. The Impact behavior and the failure mechanisms are thoroughly investigated and also the absorbed energy during projectile perforation was correlated to the damaged area of specimens. The test results show that the ballistic resistance decreases with increasing the volume fraction of microballoons and the panel with 40% volume fraction of microballoons has the highest specific perforation energy. Moreover, nano-reinforcing the syntactic foam core increased the ballistic limit velocity up to 10%.