Cancer and malaria are life-threatening diseases that pose a permanent public health problem. Existing cytostatic and antimalarial drugs are progressively losing their efficacy due to the development of drug resistance. Thus, there is a constant need for the development of novel and effective drugs. One of the possible approaches is molecular hybridization, i.e. covalent linking of two bioactive moieties into a single molecule with improved properties. In this dissertation, hybrids comprising harmin, a -carboline alkaloid with pronounced antimalarial and antitumor activity, and: 1) cinnamic acid derivatives (harmicines), 2) chloroquine (harmiquins), 3) ferrocene (harmicenes) were prepared. The harmicines were synthesized by a copper(I)-catalyzed azide-alkyne cycloaddition ("click" reaction) leading to triazole-type hybrids. On the other hand, harmiquins and harmicenes were prepared by both "click" and coupling reactions, giving triazole- and amide-type harmiquins and harmicenes. To obtain the required starting compounds for the "click" reaction, synthetic routes to -carboline-, cinnamic acid derivative-, 7-chloroquinoline-, and ferrocene-based alkynes and azides were developed. For the purpose of coupling reactions, 7-chloroquinoline- and harmine-based amines and acids were prepared. The novel compounds were characterized by standard methods (1H and 13C NMR, IR, MS). The antimalarial activity of the prepared compounds was evaluated in vitro against the erythrocytic and hepatic stages of the Plasmodium life cycle, as well as the antiproliferative activity against a panel of human tumor cell lines. Among the harmicines, triazoles 49a-e exhibited the strongest antiproliferative activity, whereas in the harmiquins series, triazoles 54 and 57 were the most cytotoxic compounds. Among the harmicenes, amide 82 showed the strongest cytotoxic activity against all tested cell lines (IC50 < 10 M), whereas triazole-type harmicenes 67, 66, and 69 displayed significant and selective activity against MCF-7 and HCT116. Harmiquins have shown the best antimalarial activity against the erythrocytic phase of chloroquine-sensitive and -resistant P. falciparum strains (IC50 in low nanomolar concentrations). Compound 63 showed a 5.5-fold stronger effect than chloroquine (IC50 = 2 ± 0.3 nM), while compound 65 was the most effective against resistant Plasmodium strains. The results suggest that harmiquins represent novel antimalarial hits, whereas further studies including harmicines and harmicenes should focus on their anticancer properties.