A series of new 3-alkoxy- or 3-hydroxy-1-[ω-(dialkylamino)alkyl]-5-nitroindazoles have been synthesized and their trichomonacidal, antichagasic and antineoplastic properties studied. Five derivatives (5, 6, 8, 9 and 17) showed remarkable trichomonacidal activity against Trichomonas vaginalis at 10μg/mL concentration. Three compounds (8, 10, 11) exhibited interesting antichagasic activity and these same compounds moderate antineoplastic activity against TK-10 and HT-29 cell lines. Unspecific cytotoxicity against macrophages has also been evaluated and only compounds 9, 10 and 11 resulted cytotoxic at the higher dose evaluated (100μg/mL), loosing cytotoxicity at lower doses. QSAR studies have been carried out. X-ray crystallographic study of compound 8 has been performed.