A simple methodology to study the interactions between ammonium- functionalized single-walled carbon nanotubes (SWNT-NH3+), free of fluorescent labels, with mammalian cells was reported. The intrinsic UV luminescence of these nanostructures by using confocal laser scanning microscopy (CLSM) with established and widely used optics was used. This powerful technique allows to remove the contribution of background fluorescence in each z-section and to digitally construct 3D images of biological specimens. In an attempt to visualize whether SWNT-NH3+ alone are capable of binding, uptake, and intracellular trafficking inside living mammalian cells, CLSM with standard optics have been used. It is also demonstrated that imaging of SWNT-NH3 is feasible by using protocols of multiple fluorescent staining of cellular compartments.