Objective: Mindfulness or the full attention state is a factor that contributes to the successful process of aging. This study aims to evaluate the evidence of validity, on the basis of the internal structure, convergent and discriminant validity, reliability and factorial invariance across gender, for the five items Mindful Attention Awareness Scale (MAAS-5) within a sample of older adults. Methods: The participants were 323 Peruvian older adults, consisting of 160 women and 163 men, whose average ages were 68.58 (S.D = 7.23) and 68.91 years (S.D = 7.12), respectively. In addition to the MAAS-5, the Satisfaction with Life Scale and the Patient Health Questionnaire-2 were administered. Results: The Confirmatory Factor Analysis indicates that the one-factor structure of the MAAS-5 presents adequate fit for the total sample (χ2 = 11.24, df = 5, χ2/df = 2.25, CFI =.99, RMSEA =.06 [90%CI:.01,.11]; and SRMR =.025), as well as for the sub-samples of men and women. This one-factor solution presents adequate internal consistency (ω = 80 [95%CI:.76 -.82]) and it is invariant across gender. Regarding convergent validity, high scores in the MAAS are associated with a greater satisfaction with life (r =.88, p<.01 [95%CI:.85,.95]) and less depression (r = −.56, p<.01 [95%CI: −.48, −.77]) in older adults. Conclusions: The preliminary results back the use of the MAAS-5 as a self-report measure of mindfulness that has an adequate unifactorial structure that is reliable and invariant across gender for measuring the full attention state in elderly Peruvians.