Porcine teschovirus (PTV) was isolated in cell culture and/or demonstrated by polymerase chain reaction in samples of brain and/or spinal cord in pigs in Indiana during the 2002-2007 period. Testing was initiated on pigs originating from populations exhibiting nervous clinical disease and/or pigs with microscopic lesions in central nervous tissues, indicating viral encephalitis and/or myelitis. Virus was demonstrated in pigs with and without lesions as well as with and without nervous clinical disease. Nucleotide sequence analysis of the 5'-nontranslated region of the viral genome revealed that these isolates had low-level genetic heterogeneity but were homologous to porcine PTV serotype 1 (PTV-1). These findings indicate that low-to-moderate virulence strains of PTV with some homology to PTV-1 are endemic in many swineherds of Indiana and are associated with subclinical and clinical nervous disease in weaned pigs.