Small airway dysfunction (SAD) appears in all asthma severities whereas a lot of studies suggest it’s association with particularly severe asthma. Currently, no single diagnostic test is available to detect and evaluate SAD. The ATLANTIS (The Assessment of Small Airways Involvement In Asthma) multi-centre study seems to be of great clinical importance. It has been suggested to include multidimensional model of SAD assessment based on impulse oscillometry, spirometry, body plethysmography, multiple breath nitrogen washout and CT scans. Combination of all these methods has been proved to be 91% effective to assess SAD in patients with asthma. The possibility of SAD evaluation might be helpful for personalisation of asthma management and targeted administration of ultra-fine particles aerosols.