Objective --To monitor the middle ear (ME) pressure continuously, day and night, in subjects with chronic central perforation (CCP) whose ears were temporarily sealed off from ambient air. Material and Methods --Twenty-three consecutive patients at our outpatient clinic, considered for myringoplasty, were studied. Results --The measurements revealed slow pressure changes with a similar pattern in 21/23 subjects. The pattern could be divided into four periods: coupling; erect body position; sleep; and the period after getting up in the morning. The coupling period was characterized by an immediate fall in pressure in 19/23 subjects and the negative pressure trend continued during most of the time in the erect position. During sleep the ME pressure initially rose and then stabilized. When the subjects got up in the morning, the ME pressure declined again. Conclusion --The different pressure periods observed in this study confirm that ME pressure regulation is a dynamic process. There is clearly a difference in the ME pressure of ears with CCP compared to previous results obtained from continuous measurements in 20 healthy ears.