Objective: This study examined the relationships between leadership style, span of control, nurses' job satisfaction and patient satisfaction, as well as the moderating effect of span of control on the relationship between leadership style and the two outcomes.

Methods: The study was conducted at seven teaching and community hospitals with a sample of 51 units, 41 nurse managers, 717 nurses and 680 patients. Data analyses included multiple regression and hierarchical linear modelling.

Results: The study findings provided support for the theoretical relationships among leadership style, span of control, nurse job satisfaction and patient satisfaction. In addition, the results showed that higher spans of control decreased the positive effects of transformational and transactional leadership styles on job satisfaction and patient satisfaction, and increased the negative effects of management by exception and laissez-faire leadership styles on job satisfaction.

Discussion: Leadership matters, and certain leadership styles, particularly transformational, are better than others. Span of control also matters: the wider the span, the lower the nurses' job satisfaction and patient satisfaction. However, as spans of control increase in size, no leadership style, even transformational, can overcome the negative effects.