This review aims to summarise our current understanding of the role of mycoplasmas in domestic dogs. Canine mycoplasmology is a small field, with less than 50 publications in the past 40 years. In this time we have gained knowledge about the number of species and have made associations with infections in dogs. However much evidence is still lacking. The importance of all canine mycoplasmas remains unknown, yet certain species are associated with canine anaemia (Mycoplasma haemocanis), respiratory disease (Mycoplasma cynos) and urogenital tract infections (Mycoplasma canis). Mycoplasmas can be isolated in pure culture from canine clinical specimens and it is hoped that this review will stimulate veterinarians to consider mycoplasmas as a potential cause of disease in dogs, especially when antibiotic therapy is failing.