The peptide melittin (MLT) is an anticancer candidate due to its lytic properties. We have synthesized MLT in which the N-terminus is labeled with Alexa Fluor 430 and also mutant MLT peptides in which Pro-14 was replaced by cysteine and labeled with Alexa Fluor 430 at this position. These two peptides were used to visualize the interaction of MLT with model membranes and HeLa cells using light and confocal microscopy. The results of haemolysis, minimum inhibition concentration (MIC) and cytotoxicity assays showed that native MLT is more toxic against both cell lines and bacteria. Giant unilamellar vesicles (GUV) of dimyristoylphosphatidylcholine and diololeoylphosphatidylcholine were used as model membranes and the MLT peptides stick onto the phospholipid bilayer. After exposure to both peptides at low concentrations, the morphology of HeLa cells changed and led to cell death. Confocal microscopy studies using HeLa cells stained with cell mask deep red revealed that, in contrast to GUV, both peptides were located inside the cells.