The relationships between the genome size and various cellular morphometric parameters have been, studied in 38 reptilian species. The nuclear volume, the cell volume and the cell surface area show a direct, linear and statistically significant correlation with the nuclear DNA content; the cell surface/cell volume ratio tends to decrease as DNA increases. The results are similar to those previously observed in Amphibia, which suggests, that at least in poikilothermic vertebrates, the correlations between DNA amounts and cell sizes are controlled by substantially similar mechanisms. A comparison of the average variations of the various morphometric parameters among each other and with the average variation of the genome size suggests that these parameters are not regulated all in the same way.