The purpose of this study was sero-epidemiological survey of porcine reproductive and respiratory syndrom(PRRS) in Dangjin area. 411 samples from 26 pig farms were analyzed by enzyme linked immunosorbant assay (ELISA). The data indicate that 66% of the pigs and 92% of the farms showed sero-positives to the PRRS viruc. Sows showed 58% of sero-positive rate and fattening pigs showed 85% of seropositive rate. The rate of sero-positive in boars was 63%. No significant regional differences were detected in sero-epidemiological survey.