Noise sources and levels were evaluated in a six-bed intensive care unit (ICU) in Athens, Greece. Ten patients (six males, four females) completed specifically designed questionnaires, and at the same time nine 8-h sound measuring sessions took place. A Bruel and Kjaer 2231 sound-meter was used on the decibel-A scale combined with observation. Human activity, operating equipment and construction engineering of the hospital building were identified as sources of noise. Noise levels were elevated [LEQ=60.3–67.4 dB(A)]. No reliable information was obtained from the questionnaires. ICU noise levels were higher by 27 dB(A) than recommended hospitals levels. To counteract noise pollution in ICUs, staff awareness and sensitivity are needed.