Abstract. Architectural acoustics of contemporary sacred buildings is still an under-appreciated issue. Many contemporary churches are not functional enough due to acoustic defects which occur there. The study discusses issues of the modern Catholic church, where acoustic problems surface as high reverberant noise levels. The building under investigation, i.e. the Church of the Visitation of the Blessed Virgin Mary, is the biggest contemporary church in Poznań, Poland, as its internal volume amounts to 16,800 m³. On the basis of in situ investigations, a computer model of the church was built and a series of simulations were carried out to determine correct treatment in order to achieve satisfactory acoustic conditions. The main assumption was to find such a solution as not to affect the modernist architecture of the church.