The main objective of this book is to provide an insight into the properties that Staphylococcal biofilm-grown cells present compared to their planktonic counterparts, evaluating the most important virulence factors of biofilm formation and PNAG production. Studies were mainly performed with S. epidermidis, followed by S. haemolyticus and S. aureus. The book is divied in three main text sections followed by two complementary sections. The first section addresses the topic of biofilm formation on clinical relevantly surfaces by clinical isolates of coagulase negative staphylococcal strains. In the second section, the topic of biofilm resistance to antimicrobial agents was addressed. Some aspects of the immune response to biofilm infections were also studied and are described in the third section. The main methods used in the experiments described in this book are compiled in the fourth section. The final section of the book provides some supplementary data and a compilation of the main conclusions of the experiments described in this book.