Out of 2384 samples, 1115 and 1361 were positive forPRRSV and TTSuV1, respectively. From the geographical distribution, PRRSV and TTSuV1 were detected from all 6 provinces, the prevalence rate was very high. This indicatesthat the two viruses are widely distributed in China, and itmight reach the distribution equilibrium to some extent.TTSuV1 detection rate in PRRSV-positive samples was>60% in 4 provinces: Jiangxi was the highest (69.5%) andShanghai the lowest (51.9%). In PRRSV-negative samples, the rate was >50% in 3 provinces: Jiangxi was the highest(55.1%) and Shanghai the lowest (33.6%). Among these, theoverall prevalence of TTSuV1 in PRRSV positive/negativesamples was 65.3% and 47.2%, respectively, and the formerrate was higher than the latter. Table 1 shows that except Shandong province, the phenomenon of the prevalence rate of TTSuV1 in PRRSV-positive was higher than negative existed in each province. The results indicate that PRRSVand TTSuV1 are widely distributed in swine in China andTTSuV1 is mostly likely to have a synergistic effect with PRRSV.