Although in the last decade the screening test of dementia have improved, is still being of interest the study of simple methods with a most sensitivity and specificity in the detection of the cognitive decline. Jorm et al have used recently a questionnaire (IQCODE) by which a subject's relative informs of the decline suffered by this in his cognitive capacity. In this work is showed a spanish adaptation of this test, the spanish-IQCODE, analysing it's usefulness for the detection of mild dementia. The S-IQCODE shows a diagnostic validity (sensitivity of 86%, specificity of 92%, positive predictive value of 54% and negative predictive value of 98%) greater than Mini-Mental State Examination (MMSE); it also shows a correlation with the diagnostic of dementia greater (r = 0.70 vs r = 0.37); and, different from MMSE, it doesn't show significative correlations with the age, the schooling and the premorbid intelligence. The results in this study show the S-IQCODE as a good test for the detection of the mild dementia, of greater diagnostic power than the MMSE and less contaminated than this by strange variables to the cognitive decline.