2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/42669In this lecture we review several cosmological issues associated with the axion. Axion solves the strong CP problem and is a good candidate for the dark matter. Limits, which are imposed by the value of isocurvature fluctuations fraction in the observed CMBR from WMAP data and the domain wall problem are discussed in a supersymmetric flat direction axion model.10 pages, LaTeX, Talk given at XII-th International School ``Particles and Cosmology'', Baksan Valley, Kabardino-Balkaria, Russia, April 21 - 27, 2003 Added references, typos correctedHigh Energy Physics - Phenomenologytext