The Ordovician documented in southeastern Europe reflects different sedimentary environments, from shallow water to basin, belonging to diverse palaeogeographical domains. Some of these geological sectors and their palaeontological content have been well described for a long time such as the Carnic Alps, which represent one of the most continuous Paleozoic sequences in the world. For some other areas, the quality of the data is variable and the knowledge is less detailed, sometimes with lithostratigraphic units still to be formalized, which also reflects the fragmentary nature of the outcrops. The Ordovician stratigraphy of southeastern Europe with its diverse successions has been revised herein and integrated with new data in an attempt to develop a global scenario for this critical time interval in the evolution of life.