Aggregation of media content comes as a popular form of media market activity which is supposed to facilitate access to information in the conditions of its excessive amount. It can be defined as selection and hierarchization of information and determination of its value. Aggregation can be performed with the direct participation of editorial teams, or it can be performed automatically, with the use of algorithms. The research conducted in April 2014 - April 2015 was to indicate the sources of information published by the news portals dominating on the Polish market, namely: Onet.pl and WP. pl. The research referred to the main section Wiadomosci (News). During the research 1829 sources of information were identified in Onet.pl and 2272 sources of information in WP.pl. Considering Onet.pl, there were 549 pieces of the portal news and 1239 pieces of news obtained from different sources. WP.pl presented 582 pieces of the portal news and 1690 pieces of news received from other sources. Thus, Onet.pl presented its original content more frequently. The scale of using external sources allows us to state that both portals are, first of all, the aggregators of medial contents, and they use external information sources, however the scale of the practice is differentiated. Generally, it is possible to state that only every third message placed in the most important section of both portals was created in their editorial offices.