SUMMARY. We have evaluated the use of sheep red-blood cells stabilised in various ways in indirect haemagglutination tests on the sera of 21 surgically confirmed cases of echinococcosis, and on control sera. Tests with Double-Aldehyde-Stabilised cells-treated sequentially with pyruvic aldehyde, tannic acid and glutaraldehyde-were more sensitive than tests with the cells treated only with formaldehyde, glutaraldehyde or pyruvic aldehyde, and subsequently tanned.