The presence of porcine astroviruses in diarrheic and healthy pigs has been reported, however, the consequences of the astrovirus infection during the weaning process have not been described.In this study, eight healthy conventional newly-weaned piglets were used to evaluate effects of astrovirus infection during the first five days.Four piglets were infected with the porcine astrovirus PoAstV/PUJP5 strain and the other four represented the control group.Body weight, rectal temperature, diarrhea and other clinical signs were monitored every 24 hours.The results showed that all animals gained body weight, the occurrence of mild diarrhea on the 3 rd day post-infection, and the astroviral presence in diarrheic samples.On the 5 th day post-infection all the piglets were euthanized and then intestinal and extra-intestinal tissues were analyzed for the presence of PoAstV/PUJP5.The cytoplasmic antigen of PoAstV/PUJP5 was observed in the enterocytes of infected piglets from jejunum, ileum, colon and in inflammatory cells from mesenteric lymph nodes.In addition, villi atrophy, fusion, epithelial hyperplasia and incipient virus detection in mesenteric lymph were observed.RNAemia could not be proved.This study shows for the first time the effects of porcine astrovirus infection on conventional newly-weaning piglets.