Bacterial diseases in poultry are well known for their negative consequences on animal health, welfare and public health. Recent advancement in scientific research has substantially improved our understanding of pathogen attributes and disease mechanism, thus progress has been made in identification and typing of bacteria with consequences on vaccine development, although substantial gaps remain. In various countries, legislation and husbandry practices for poultry production have changed recently with prevention strategies gaining more attention in order to reduce treatment options due to increasing concerns about antimicrobial resistance. However, challenges prevail due to changing landscape of bacterial diseases, which demands for continuous epidemiological investigations and a thorough understanding of disease influencing mechanisms. More standardized experimental studies aligning the knowledge from clinical cases should be implemented to understand the gaps in host-pathogen interaction in a controlled set up. Overall, the chapter aims to provide advances and challenges related to bacterial infections in poultry.