A Crimean hemorrhagic fever-Congo (CHF-C) virus antibody survey was carried out in Iran with sera from man and several animal species; this survey was done by means of agar gel diffusion precipitation (AGDP) test with the following results (percent positive of number tested): men, 13% of 351; sheep, 38% of 728; goats, 36% of 135; cattle, 18% of 130; camels, 0% of 157; small mammals, 3% of 274. A number of sera were tested by complement-fixation (CF), neutralization (N), and hemagglutination-inhibition (HI) tests in addition to the AGDP test. A good correlation was found in the results with 105 sera tested by AGDP, HI, and N, with approximately 70% to 75% positive in all three tests; by CF, only 20% were positive. Of 55 human sera, of which 15 could be tested by N test, about half were positive by AGDP and only 10% by HI at low titers; none was positive by N and CF tests. These results suggest that any one of the three serological tests (N, HI, and AGDP) can be used to survey the antibody prevalence in sera from domestic animals; the CF test, not unexpectedly, was less suitable. Our results, however, are inconclusive in regard to the human sera.