Positive organs in the past belonged to the most common small instruments built namely in churches of little towns and villages in Slovakia. The submitted study presents the results of an organ research on a positive organ coming from 1698, built in the Roman-Catholic church of the Visitation of the Blessed Virgin Mary in Mokra Luka in the region of Central Gemer. This instrument is one of the oldest completely preserved historical organs in Slovakia. It is distinguished by a rich beautiful sound resulting from the specification of the instrument comprehending an organ stop very unique for the time, (Heltig) Quinta 2 2/3', with pipes completely made of wood and lacking any breaks. Pipes of organ stops made of pipe metal include a significant portion of tin; 88.42 % in pipes of organ front and 72.67 % of tin in inner pipes.