Abstract: Effective leadership, organizational culture, and structure are essential for optimal service delivery in public service organizations. This study sought to evaluate the Impact of Leadership, Culture, and Structure on Service Delivery in Kenya's Defence Forces Medical Insurance Scheme (DEFMIS). Specifically, it sought to: investigate how organizational leadership influences service delivery at, determine how organizational culture impacts service delivery at DEFMIS and finally, establish how the organizational structure affects service delivery at DEFMIS. DEFMIS operates under a top-down, bureaucratic model inherited from the military. The study used a descriptive survey research design. Data was collected through 7 key informant interviews (KIIs) comprising top management, departmental heads, and healthcare providers. The study revealed that DEFMIS’s top-down leadership style enforces accountability yet limits prompt decision-making and restricts innovation, often leading to delays in healthcare services. Despite this, DEFMIS is noted for its commitment to patient welfare, as reported by healthcare providers. The centralized structure, while maintaining control, creates inefficiencies in claim approvals and slows technological adoption, impacting the quality and timeliness of care. The study provides insights into DEFMIS's operational challenges, emphasizing the need for transformational leadership, a customer-centered culture, and a decentralized structure to enhance service delivery. These findings extend relevance to other public service organizations seeking to improve performance through leadership, culture, and structural adaptations.

Key words: Leadership Style, Organizational Culture, Service Delivery, DEFMIS, Healthcare Structure.