During a period of 6 months, 537 pregnant women from a rural area in Saudi Arabia were tested serologically for brucellosis. Of the 513 women who were tested routinely, 18 were found to have a positive titre (3.5%). Of 24 patients in whom the test was carried out because of symptoms suggestive of brucellosis, all were positive. Thirty of the 42 positive cases had titres exceeding 1:160. The incidence of abortion among pregnant women with Brucella titres less than 1:160 was 7.7% contrasting with 17.6% among those with titres above 1:160 (P less than 0.04). This observation calls for further study of the incidence of brucellosis in pregnant women in infected areas, and the connection between elevated Brucella titre and abortion.