The indirect microimmunofluorescence test was used to determine the presence of antibodies to phase I and phase II Coxiella burnetii antigens in New Brunswick and Prince Edward Island cats. Twenty of 104 (19.2%) New Brunswick cats tested had antibodies to phase II antigen; five of these (4.8%) also had antibodies to phase I antigen. Six of 97 (6.2%) Prince Edward Island cats tested had antibodies to phase I and phase II antigens. Our data suggest that cats may be important in the epidemiology of Q fever in these provinces.