Frontiers in Computational Chemistry presents contemporary research on molecular modeling techniques used in drug discovery and the drug development process: computer aided molecular design, drug discovery and development, lead generation, lead optimization, database management, computer and molecular graphics, and the development of new computational methods or efficient algorithms for the simulation of chemical phenomena including analyses of biological activity. The fifth volume of this series features these six chapters: - Recent Advances and Role of Computational Chemistry in Drug Designing and Development on Viral Diseases- Molecular Modeling Applied to Design of Cysteine Protease Inhibitors – A Powerful Tool for the Identification of Hit Compounds Against Neglected Tropical Diseases- Application of Systems Biology Methods in Understanding the Molecular Mechanism of Signalling Pathways in the Eukaryotic System- Implementation of the Molecular Electrostatic Potential over GPUs: Large Systems as Main Target- Molecular Electron Density Theory: A New Theoretical Outlook on Organic Chemistry- Frontier Molecular Orbital Approach to the Cycloaddition Reactions