Equine rhinitis B virus (ERBV), genus Erbovirus, is most closely related to the Cardiovirus genus in the family Picornaviridae. The structural proteins (VP1–4) of erboviruses are not well described, but are predicted by sequence to be 35, 29, 26 and 7kDa. Methods for the purification of cardioviruses (polyethylene glycol, trypsin treatment) were used to characterise the structural proteins of ERBV1. Only one of the virus proteins detected was an expected molecular mass, and this 26kDa protein was identified as VP3 by N-terminal amino acid sequencing. N-terminal sequencing of the 56 and a 29kDa protein identified sequences consistent with VP2 and VP1 respectively, despite these being 27kDa larger and 6kDa smaller than predicted. Virus purified without trypsin showed proteins more consistent with masses predicted for VP1, VP2 and VP3 at 35, 29 and 26kDa respectively. These proteins were further identified with antibodies affinity purified to recombinant VP1, VP2, VP3 produced in E. coli. Interestingly, antibodies affinity purified to the non-structural protein 3C pro , produced in insect cells, strongly detected a 27kDa protein in western blots of virus purified with and without trypsin treatment, suggesting the non-structural 27kDa 3C pro co-purifies with ERBV1 virions.