AIM:To evaluate the effects of central corneal thickness (CCT) on 24-hour intraocular pressure (IOP) fluctuation. METHODS: Measurements of IOP were obtained by Goldmann applanation tonometer on 5am,7am,10am,2pm,6pm,and 10pm during a 24-hour period from 39 untreated glaucoma patients and 44 age-matched normal control subjects. CCT was measured in all subjects using ultrasound pachymetry. The association between IOP fluctuation (peak IOP-trough IOP) during the 24-hour period and the CCT was assessed in both glaucoma patients and healthy age-matched controls using Spearman correlation. RESULTS: The average 24-hour IOP, peak IOP, IOP fluctuation and CCT in glaucoma group and control group were 21.33±2.91mmHg and 16.19±2.33mmHg（t=12.615，P=0.000）, 24.67±2.72mmHg and 18.55±2.45mmHg（t=12.613，P=0.000）, 6.63±3.26 mmHg and 4.72±1.60mmHg（t=4.709，P=0.000）, 544.44±32.11μm and 537.16±27.66μm（t=1.569，P=0.119）, respectively. The average 24-hour IOP, peak IOP and IOP fluctuation were significantly different between normal and glaucomatous patients. The CCT, however, was not significantly different between the two groups. There was no statistically significant correlation between IOP fluctuation and CCT in glaucomatous (r=0.140，P=0.222) and normal subjects (r=0.050，P=0.642). There was no significant difference in average 24-hour IOP, peak IOP or IOP fluctuation between glaucomatous patients and normal subjects with thick(CCT≥545μm) and thin corneas(CCT＜545μm). CONCLUSION:Twenty-four-hour IOP fluctuations are not correlated with CCT measurements in glaucoma patients and normal subjects.