Abstract: A transectional Surveillance was carried out in 384 villages of 12 counties in west Hubei where filariasis had been basically endicated 2-3 years ago.Among 155 235 persons surveyed in an area with bancroftian filariasis, 107 micro-filaremic patients were found by blood examination, the average microfilaremia rate (MFR) being 0.07%. However, MFR was as high as 1.31 and 1.91% in 2 villages, being slightly above the parameters used for "basical eradication" of filariasis, the highest microfilarial density was 40 mff/120μl and only l out of 2 785 Culex pipiens fatigans dissected was found harbouring 2nd stage larvae. The authors deemed that in such areas, Surveillance should be strengthened.Concurrently another follow-up observation in areas of malayan filariasis with 64 041 persons from 74 villages was carried out. The results showed that only one patient who had never been examined was found positive by blood examination, the average MFR being 0.0016%, the MFD being 7 mff/120μl. Dissection of 2 706 Anopheles sinensis failed to find larval infection. These results suggest that filariasis transmission in this area has been interrupted, the main task in the later Stage of controlling filariasis is to treat those patients with symptoms and signs.