Background: Few studies have estimated the economic cost of dementia in Latin America and there is scant research on how this cost may vary across different socioeconomic status (SES) groups. Objetive: Study the economic cost of dementia in Chile, and its variation according to SES. Patients and methods: 391 informal primary caregivers fullfilled the RUD-Lite and a SES questionnaire. The cost is decomposed into direct medical costs (medical care, drugs, exams), direct social costs (social service, daycare) and indirect costs –mostly associated to informal care. The study was approved by the Ethical and Scientific Committee - SSMO. Result: Mean monthly cost per patient is 915 USD. Direct medical costs account for 20 per cent of the cost; direct social costs are 5 per cent of the total and indirect costs is 75 per cent of total cost. The mean monthly cost is inversely related to SES. The monthly cost for the high SES is 696 USD while for the low SES it’s 1021 USD. Conclusion: Direct medical costs increase with the SES of patients - reflecting differences in purchasing power-, indirect costs are inversely related to SES and more than compensate differences in medical costs. In lower SES groups, informal care is mostly provided by female caregivers who are inactive in the labor market. Compared to other HIC countries, the averaged cost is lower (10980 versus 32865 USD) and the distribution of informal cost is higer (70% versus 40%), consistent with the absence of universal coverage of dementia and a coherent public health response.