Coronavirus are single-stranded plus-strand RNA viruses that cause several respiratory and neurological diseases in a wide range of animals and humans. There are 4 main groups of Coronaviruses: alpha, beta, gamma and deltacoronavirus, where gamma and deltacoronaviruses have been found in wild birds. This study evaluated the epidemiology and phylogeny of coronavirus in Swedish waterfowl in order to increase the existing knowledge of these viruses in nature. The RNA-dependent RNA polymerase gene of 36 different samples from Mallards collected from Ottenby Bird Observatory, Sweden (56°12’58”N 16°24’40”E) in 2011 were sequenced. These sequences were characterized and compared to other gammacoronaviruses using a phylogenetic approach. Analysis revealed that there is diversity of sequences from the samples as there was evidence of at least 4 groups of RNA-dependent RNA-polymerase sequences. A difference of sequences over time was also detected which might suggest virus turnover due to host herd immunity. However, the results doesn´t demonstrate a clear pattern of reinfection with the same or different RNA-dependent RNA sequences within individuals over time. This study has contributed 1/3 of all gammacoronavirus sequences, and demonstrates the need in finding a method to complete genome sequence these viruses. Comparative genomic studies are important to determine the diversity of virus gene lineages and viral phenotypes, and also to be able to understand the relations behind interclass jumping, which is important to predict and avoid pandemics that coronavirus might cause.