This chapter examines the dynamics of speak-up culture in the Intensive Care Unit (ICU) of a Hong Kong hospital, focusing on intra- and interdisciplinary communication among doctors and nurses. Using a combination of audio-recorded observations and semi-structured interviews, the study uncovers key factors influencing communication openness and teamwork quality. Findings highlight significant barriers to speaking up, such as hierarchical structures, time constraints, and cultural norms, particularly for nurses in interdisciplinary interactions. Despite these challenges, fostering a robust speak-up culture is critical for enhancing patient safety and care quality in high-stakes clinical environments. The chapter offers practical recommendations, including leadership engagement, communication training, and strategies to bridge hierarchical and cultural divides, aiming to create an inclusive environment where open dialogue and mutual respect thrive.