Abstract: This paper presents a new high-level synthesis (HLS) approach which addresses the problem of synthesis of conditional behaviors. In proposed methodology, the conditional behaviors are represented by Hierarchical Conditional Dependency Graphs (HCDG) and synthesized using derived Constraints Logic Programming (CLP) models. Our synthesis methods exploit multicycle operations and chaining as well as conditional resource sharing and speculative execution at the same time. These techniques are essential in HLS and the experiments carried out using the developed prototype system showed good performance of the synthesized designs and proved the feasibility of the presented approach.