The purpose of the study was to determine how and when the personnel of the Finnish National Opera are exposed to noise and whether exposure depends on musical selection of repertoire. Additionally, an evaluation of sound exposure level due to individual rehearsals was included. The measurements were done using individual noise dosimeters and fixed-point measurements. From the measurements, annual noise exposure in the Opera was evaluated. The conductors, dancers, and double bass players were exposed to levels below 85 decibels, A-weighted, dB(A), which is the national action level. The choir members were exposed to sound levels of 92 and 94 dB(A). Within the orchestra, the highest sound exposure levels were found among percussionists, 95 dB(A); flute/piccolo players, 95 dB(A); and brass players, 92-94 dB(A). Other sound exposure levels among orchestra members varied from 83 to 89 dB(A). Soloists and rehearsal pianists are likely to be exposed to sound levels exceeding the national action level. From an exposure perspective, the individual rehearsals, 79-100 dB(A), proved to be as important as performances and group rehearsals, 82-99 dB(A), among orchestra musicians and choir singers. The ambient sound level for the lighting crew was 76 +/- 4 dB(A). However, the measured sound levels at the ear varied from 77 to 92 dB(A) due to the communication via headphones that had individual volume control. For the majority of personnel of the Finnish National Opera, sound exposure level exceeded the national action level value of 85 dB(A). Artists exceeded the action level during both individual and group rehearsals, as well as during performances. Hearing protection has been designed for musicians. Education/reinforcement is required to ensure it is worn.