Many digital libraries use hierarchical indexing schema, such as MeSH to enable concept based search in the retrieval phase. However, improving or outperforming the traditional full text search isn’t trivial. We present an extensive set of experiments using a hierarchical concept based search retrieval method, applied in addition to several baselines, within the Vaidruya search and retrieval framework. Concept Based Search applied in addition to a low baseline is outperforming significantly, especially when queried on concepts in the third level and using disjunction within the hierarchical trees.