Objective: The main objective of the study was to evaluate the influence of a novel modification of the Wurster draft tube on the particle coating performance. Modification embodies enabling of the additional radial flow of pressurized air through the perforations in the draft tube inner wall. Materials and methods: After coating the neutral pellets with polymeric solution, comprising colouring agent, pellet batches were characterized for coating variation, yield and degree of agglomeration. By employing the piezoelectric probe flow regime zones and particle number density profiles inside the draft tube were evaluated, utilizing the power spectral density and particle impact frequency analysis of captured signals, respectively. Results: The results clearly indicate that the additional radial airflow improves the coating uniformity, expressed by the relative standard deviation (RSD) value of the dye amount dispersed in the coating layer of each set of pellets. Lower RSD values were noticed in the case of pellets coated using a classic Wurster (CW) chamber equipped with a perforated draft tube (CW-P) compared to the reference experiments conducted with a conventional draft tube; regardless of the air flow rate (105, 130 or 156 m(3)/h) and the gap size (10 or 20 mm). As demonstrated in our previous studies, swirling inlet airflow (SW) contribute to much more uniform per particle deposition of the coating material when compared to CW process. By utilizing the SW chamber equipped with a modified draft tube (SW-P), the significant improvement in the coating uniformity was achieved at the gap size of 20 mm, regardless of the air flow rate. In the case of additional air flow through the draft tube perforations, additional number of inner tube zones, possessing predominant particle fluctuation frequencies in the range from 1 to 5 Hz, were noted. By utilizing the modified draft tube the lower number of the particle impacts in comparison to coater equipped with the conventional Wurster draft tube were recorded, regardless the coater type. (C) 2018 Published by Elsevier B.V.