A leading hallmark of Alzheimer’s disease is the formation of neurofibrillary tangles (NFT’s) in the neurons of our central nervous system. NFT’s are almost entirely accumulations of insoluble microtubule-associated protein tau fragments. Tau is a highly disordered protein and its normal function seems to be the assembly and stabilization of microtubules in neuronal cells. In the adult human brain, tau exists in six different isoforms that possess either three or four imperfect repeats constituting the microtubule-binding domains. Previous studies have analyzed tau function in vitro: however it is unclear how tau induces microtubule bundling at physiological conditions. Herein, we compared how different tau isoforms and tau protein fragments induce bundling of microtubules at physiological conditions. Different tau isoforms, mutants and deletion constructs were synthesized using expression vectors in E. Coli bacteria. Once purified, tau and tubulin were mixed and polymerized to form microtubule bundles. Our previous work determined the structure of these microtubules using reciprocal-space imaging techniques. This current study imaged these microtubule structures using real-space imaging techniques to complement the reciprocal-space technique. With this approach, we were able to observe and confirm that all wild-type isoforms induce microtubule bundling. Some fragments and deletion constructs induced bundling as well. These experiments allow us to characterize tau dysfunction in context of the microtubule-tau complex. Furthermore, understanding the functional properties of tau fragments and deletion constructs enables us to find out the structural dependence of certain segments of the protein. We hope that this data provides insights to the discovery of new ways to combat Alzheimer’s disease.