Aurora Kinases are a family of serine-threonine kinases which have three members, Aurora A, Aurora B, and Aurora C. Aurora A is localized on the centrosome and spindle fibers, Aurora B is a part of chromosome passenger complex (CPC), and changes localization throughout mitosis from kinetochores to midbody, while Aurora C is present in germ cells only and shares similar location to Aurora B as a chromosomal passenger protein. Aurora A plays a significant role in the cell cycle through regulation of bipolar spindle assembly, centrosome duplication and separation, and G2/M phase transition. Overexpression and amplification of Aurora A have been reported in many cancers as it promotes the proliferation of cancer cells. Thus, in cancer therapeutics, Aurora A is a crucial target, and several Aurora A inhibitors are being developed for the treatment of various cancers. The objective of this project was to characterize previously identified naphthoquinones by our lab, as novel Aurora A inhibitors. Antiproliferative activity of 8 naphthoquinones was determined via SRB proliferation assay. HH-185 was the most potent naphthoquinone with GI50 in 0.127µM in HCT116 (colon carcinoma) cell line. An in vitro kinase assay showed that HH-185 inhibited Aurora A selectively compared to Aurora B with IC50s of 90.5 and 351.3 nanomolar, respectively. Treatment of cells with HH-185 resulted in Aurora A phenotype with the increase in mitotic cells containing monopolar spindles. Treatment of cells with HH-185 also resulted in increased cleavage of PARP, an apoptotic marker. HH-185 and closely related small molecular weight naphthoquinones can, therefore, serve as fragments for designing and optimizing Aurora A specific inhibitors.