To provide a preliminary assessment of the prevalence of dementia and its subtypes in a rural area. From a total of 2,469 people over 65 who were not committed to any institution, 273 were randomly chosen and stratified by age and sex. Of these 273 individuals, 244 (89.4%) took part in the study. Family doctors administered the miniexamen cognoscitivo (MEC), a Spanish version of the Mini Mental State Exam to screen all individuals taking part in the first phase. Enrolled in the second phase were all those whose scores on the MEC were below the cut-off point, plus a similar number of individuals whose scores were above this level and who were used as controls. The CAMDEX was the instrument used for diagnosis by clinical psychologists. The overall prevalence of dementia in the area under study was 13.93 +/- 4.34%. This prevalence includes the three levels of diagnosis certainty for CAMDEX (definitive, probable and possible) and the three levels of severity (minimum, mild, moderate, and severe) defined by the instrument. The number of individuals with dementia increased with age. Females showed more dementia than males in all age groups. The distribution of dementia by subtypes was 41.18% for both Alzheimer's type senile and presenile forms, and for vascular dementia, and 17.64% for mixed dementia. Our results show a prevalence of dementia that is higher than rates observed in other studies using similar materials and methods.