The synthesis of several new pyrazole and indazole derivatives from acetophenone and tetralone substrates is reported. The bioactivities of the new compounds were evaluated through in vitro assays for endothelial cell proliferation and tube formation. Results herein indicate that the easily prepared compounds containing the indazole structural framework exhibit potent cytostatic properties against all cell lines tested, with compounds 13 and 14 being the most active displaying IC(50) values of 1.5 ± 0.4 µM and 5.6 ± 2.5 µM, respectively, against MCF-7 cells. In addition, the indazole derivative 16 was assessed as a competent inhibitor of endothelial tube formation at 30 µM.