Investigations were carried out to identify the causative agent of acute diarrhea, respiratory distress, and polioencephalomyelitis of pigs on a swine farm in Shanghai, China. Samples from the affected animals were tested for viruses and bacteria that are known to cause similar symptoms in swine, and only porcine sapelovirus (PSV; designated as csh strain) was isolated. The presence of PSV was further confirmed by the specific cytopathic effects observed in susceptible cells and by the results of PCR and electron microscopy. Nucleotide sequencing and phylogenetic analysis showed that this isolate is PSV. When inoculated into healthy pigs, PSV.csh caused the same symptoms as observed in the affected herd. Therefore, PSV.csh is the causative agent of this disease. To the best of our knowledge, this is the first report of PSV infecting piglets in China.