This book contains six chapters on the chemistry of pyrimidine derivatives. Chapter one sums up the pharmacological potential of pyrimidine derivatives and provides an overview of recent studies of these unique compounds as anti-inflammatory agents. Chapter two covers various pyrimidine derivatives with powerful biological and pharmacological applications. The authors in chapter three answer the question of how pyrimidine bases formed on the Earth, i.e., how they evolved. Chapter four begins with an introduction to pyrimidine’s structure and then delves into the diverse reactions of pyrimidine derivatives. Chapter five presents the applications of pyrimidine derivatives in the adsorption of heavy metals, which are environmental pollutants. The final chapter provides readers with an assessment of the molecular targets linked to cancer, aiming to clarify their role in disease advancement and the possibility for treatment.