Assembly is a hierarchical process. It involves the construction of subassemblies and their assembly with other subassemblies and components. A product is split in subassemblies at the design stage as it is not practical to handle the design of the whole product. Splitting the assemblies into subassemblies has the advantage of modularity in design, manufacturing and assembly. Most complex assemblies tend to include a number of subassemblies. There exist methods to extract assembly mate information but identifying subassemblies within the assembly remains a challenge. There is a need to identify subassemblies automatically without human interference. This paper aims at detecting the subassemblies by making use of Application Programming Interface (API) of the computer aided design (CAD) software. © Research India Publications.