Sex and gender exert profound influences on health outcomes, shaping susceptibility to illnesses, disease manifestation, treatment responses, and overall well-being. While sex refers to biological characteristics, gender encompasses socially constructed norms and roles. This chapter explores the intricate intersections of sex and gender within the context of health and diseases, focusing on noncommunicable diseases (NCDs) with an emphasis on mental and brain health. It delineates how sex-specific genetic, epigenetic, and hormonal influences generate distinct physiological environments, impacting disease susceptibility and progression. Furthermore, it highlights gender-specific disparities in healthcare access and outcomes, emphasizing the need for inclusive and patient-centered approaches. Through examples from NCDs and neurological diseases, it elucidates sex and gender differences in disease incidence, risk factors, and treatment responses. The chapter underscores the importance of considering sex and gender in medical research, clinical practice, and health policy to achieve equity in healthcare outcomes. Efforts to enhance sex and gender considerations in research, alongside addressing health disparities, will advance toward achieving equitable healthcare for all.