The present study explores the possibility of using ultrasonic treatment for the conversion of dendritic microstructure of in-situ A356/TiB2 composite into non-dendritic globular structure. A356/2TiB2 in-situ composite has been subjected to high intensity ultrasonic treatment in liquid metal state as well as during the process of solidification. Microstructural analysis shows that the ultrasonic treatment during the process of solidification is an effective technique for the transformation of dendritic morphology into fine globular structure along with the modification of Si needles. © 2015, The Indian Institute of Metals - IIM.