Organizational structure has been changing fast in recent years and it seems likely that this trend will continue. The main impetus has come from changes in the business environment, which has moved from being a relatively stable and static one to one characterized by complexity, uncertainty, dynamism, and competition. Changes in the business environment have occurred in 4 main areas - political, economic, technological, and social. Trends in organizational structure are downsizing, changes in job design, team mechanisms, and increased responsibility and decision making. The cluster structure is a radical and innovative form of organizational structure consisting of collections of workers undifferentiated by rank or job title who operate together on a semi-permanent basis with no direct reporting relationships and only a residual hierarchy. Cluster-like structures, while exhibiting similar characteristics to the cluster, offer a step-by-step route to organizational restructuring. Cases of the cluster and cluster-like structures in British Petroleum Engineering and TEAM Aer Lingus are presented.