Wild polioviruses are the naturally occurring strains of poliovirus that circulate in the environment.

There are three serotypes of wild poliovirus: type 1, type 2, and type 3. Immunity to one serotype does not confer immunity to the other two. Outbreaks were largely unknown prior to the 20th century. However, with improved sanitation in the 20th century, the average age at which individuals were exposed to the virus increased. With progressively declining protection from maternal antibodies, infection increasingly resulted in paralysis.

Type 2 wild poliovirus was declared eradicated in September 2015, with the last virus detected in India in 1999. Type 3 wild poliovirus was declared eradicated in October 2019. It was last detected in November 2012. Only type 1 wild poliovirus remains.