For oesophageal epithelial changes to develop from gastro-oesophageal reflux disease (GORD), the character of the refluxate must be acid enough to cause injury. Experimentally, copious perfusion of the oesophagus with weak acid is quite harmless. However, hydrochloric acid alone with a pH below 3.0 may cause oesophageal injury. Cola drinks are strongly acidic (pH 2.5), This study analyses the influence of and possible interaction between cola consumption and oesophagitis, Twenty rats were divided into two groups of 10. The animals received saline (pH 7.0) or cola (pH 2.6) per OS with 24 h free access to these solutions. After the experiment the oesophagus was dissected. The mucosa was macroscopically and histopathologically examined, and how cytometric analysis was used to look for proliferative activity. The histopathological analysis showed that there is no difference between saline and cola. But the findings of cell cycle anal? sis showed that the effects of cola and saline in inducing oesophageal mucosal damage are different. In the cola group the values were G(0)/G(1), 7.33 +/- 2.88; S, 29.88 +/- 2.88; G(2)/M, 0.10 +/- 0.01; PI (proliferative-regenerative index), 29.76 +/- 2.88. The rat cell population g(0)/g(1) phases were found to he low (p < 0.01), and the cell population S and PI phases were found to be significantly elevated compared with the control group (p ( 0.01). (G(0)/G(1), 79.30 +/- 5.97; S, 16.06 +/- 8.27; G(2)/ M, 4.66 +/- 1.03: PI, 20.03 +/- 6.01). These results: Here reflected in the proliferative index, which is used as a measure of the regeneration index, The data show that cola has proliferative and regenerative effects on the oesophageal mucosa, and it is possible that its regenerative effect is caused as a result of an irritant effect.