The empirical study analyses the potential for positive external effects from foreign investors in favor of domestic firms using the IWH-FDI micro database and taking into account firm-specific characteristics of foreign investors in selected Central and East European countries as well as in Eastern Germany. The analysis shows that only half of the foreign investors believe that they are important for technological activities in domestic supplier firms. Thereby, the potential for external positive effects is higher in Central and Eastern Europe than in Eastern Germany. A reason for this might be that supplier firms in Eastern Germany already operate on a clearly higher technological level than their counterparts in Central and Eastern Europe. Taking into account the share of domestic supplies of foreign investors, it shows that the potential for positive external effects increases only to a certain point from which on the spillover potential stagnates or even declines. Furthermore, there is clear evidence for the following characteristics of foreign investors to increase the potential for positive external effects: innovativeness of the foreign investor, internal and external technological cooperation of foreign investors, independence from the headquarters in research and development issues and market entry through acquisition (instead of greenfield investment). The share of foreign participation as well as the duration of presence in the host economy does not show any statistically significant effect on the potential for external effects. Policy makers should therefore not only aim at the settlement of employment intensive foreign investors, but also and particularly support investors that are characterized by technological activity and regional integration.