Malaria and leishmania are very common parasitic diseases of the developing world and drugrnresistance has hindered their efficient control. Pyrazole derivatives were synthesized usingrnaldol condensation and subsequent cyclization reactions. The compounds were synthesized inrna good yield (71.39%-95.23%). The compounds were purified by recrystallization and theirrnchemical structure was characterized by elemental microanalysis, IR, and 1HNMRrnspectroscopy. In vivo antimalarial and in vitro antileishmanial activity was conducted usingrnfour day suppression test and Alamar blue reduction method, respectively.rnThe results for antimalarial activity conducted using P. berghei infected mice at a dose levelrnof 48.46Î¼mol/kg/day showed that all the synthesized compounds have lower activity than thernstandard drug chloroquine phosphate. Compound IIc, 1-phenyl-4-(3-(thiophen-2-yl)-4,5-rndihydro-1H-pyrazol-5-yl)-3-p-tolyl-1H-pyrazole, showed relatively the highest %rnsuppression, 63.40%. The result for antileishmanial activity test revealed that all thernsynthesized compounds except compound IIb had better antileishmanial activity than thernstandard drug miltefosine (IC50= 3.1911 Î¼g/ml). All of the synthesized compounds exceptrncompounds III and IIIb exhibited lower antileishmanial activity compared to the standardrndrug amphotericin B deoxycholate (IC50=0.0460 Î¼g/ml). Compound IIIb, phenyl pyrazolinernwith propanoyl side chain, 1-(3-phenyl-5-(1-phenyl-3-p-tolyl-1H-pyrazol-4-yl)-4,5-rndihydropyrazol-1-yl)propan-1-one, was found to be the most active (IC50= 0.0112) and twornhundred eighty five and four fold more active than the standards miltefosine andrnamphotericin B deoxycholate, respectively.rnKeywords: pyrazole, in vivo antimalarial activity, in vitro antileishmanial activity.