This study investigated the prevalence of mental health problems after a major bushfire in Australia and examined the validity of the General Health Questionnaire (GHQ) (Goldberg 1978) against the Anxiety, Affective and Post-Traumatic Stress Disorder modules of the Diagnostic Interview Schedule (DIS; Robins et al. 1981). Study 1 was carried out 12 months after the Ash Wednesday bushfires and sought to include all the victims of the fires. Study 2 was conducted 20 months after the fires and included a sample of victims who had experienced major losses in the fires. Twelve months after the fires, 42% (n = 1,526) of the victims were defined as a potential psychiatric case using the GHQ. This rate indicated a significantly greater level of morbidity than found in communities that have not experienced a natural disaster. Twenty months after the fires, 23% (n = 43) were defined as "cases". The 28-item GHQ was found to be a valid instrument for defining the presence of psychiatric disorder in a disaster-effected community. The findings demonstrated that lasting psychiatric morbidity is associated with natural disasters.