There is an increasing role of online social networks in the life of young Poles. We conducted a large-scale survey among Polish former Erasmus students. We have received 2450 completed questionnaires from alumni of 115 higher education institutions all over Poland. 85.4% of our respondents reported they kept in touch with their former Erasmus colleagues. Unsurprisingly, it is the social networking website communication that largely prevails as the most frequent communication channel. Almost 2/5 of the study subjects considered it to be the most used in this context. We were interested in the patterns of use of social networking websites among our respondents. Although 10 social networks were included in the catalogue of answers, it turned out that only 4 of them played a significant role in our sample. The most popular was Facebook, which was number one in socialising with both local and international friends. LinkedIn and GoldenLine.pl were reported to serve mainly for professional purposes, including job searching and maintaining a professional network. The use of nk.pl was confined to contacts with local friends. 514 respondents, i.e. 21.7%, said they had created a group in a social networking website to keep in touch with former Erasmus student friends.