The incursion of the human pandemic influenza A virus H1N1 (2009) (H1N1 pdm) into pig populations and its on-going co-circulation with endemic swine influenza viruses (SIV) has yielded distinct human-porcine reassortant virus lineages. The hemagglutinin (HA) gene of H1N1 pdm was detected in 41 influenza virus positive samples from 7 swine herds in the Northwest of Germany in 2011. Eight of these samples yielded virus which carried SIV-derived neuraminidase N2 of three different porcine lineages in a H1N1 pdm backbone. The HA sequences of these viruses clustered in two distinct groups and were distinguishable from human and other porcine H1 pdm by a unique set of eight non-synonymous mutations. In contrast to the human population where H1N1 pdm replaced seasonal H1N1, this virus seems to co-circulate and interact more intensely with endemic SIV lineages giving rise to reassortants with as yet unknown biological properties and undetermined risks for public health