Comet assay or single-cell gel electrophoresis is a widely used method for DNA damage assessment. The results of the method can be scored under microscopic examination either with the naked eye or by automated systems. In this study, we present a semi-automatic comet assay analysis tool that was developed in our laboratory. The results obtained with our tool were compared with that of fully automatic shareware software. The preliminary results suggest that the presented semi-automatic software is an accurate and reliable tool for evaluation of comet assay.