Pyocyanin (PCN) is a blue redox-active secondary metabolite that is produced by Pseudomonas aeruginosa. PCN is readily recovered in large quantities in sputum from patients with cystic fibrosis who are infected by P. aeruginosa. Despite in vitro studies demonstrating that PCN interferes with multiple cellular functions, its importance during clinical infection is uncertain. This is partially caused by the difficulty in defining the contribution of PCN among the numerous virulence factors produced by P. aeruginosa during infection. In addition, few cellular pathways that are affected by PCN are known. This review briefly highlights recent advances that might clarify the role of PCN in P. aeruginosa pathogenesis.