Malaria still remains to be a public health threat and one of the most important infectious diseases to get attention from World Health Organization. No domestic malaria cases have been reported on the island of Cyprus since 1948, as a result of successful elimination process. All of the malaria cases detected in recent years are imported cases. As known, hundreds of medicines are obtained from plants and traditional medicine are used in endemic places of malaria. The cause of malaria - Plasmodium parasites, are developing resistance to antimalarial drugs. Hence, research on plant extracts and essential oils have gained great interest in recent years to obtain new and safe agents/substances. In our study, it was aimed to investigate the in vivo antimalarial activities of essential oils obtained from Origanum dubium, Origanum majorana, Salvia fruticosa and Laurus nobilis plants which grows in Northern Cyprus against Plasmodium berghei - the rodent malaria agent. Plants were collected in appropriate seasons and were dried to obtain and analyze essential oils via Clevenger Apparatus system. L929 mouse fibroblast cell line and MTT [3-(4.5-dimethylthiazole-2-yl) -2.5-diphenyltetrazolium bromide] kit were used to determine the cytotoxic activities of the essential oils obtained. In our study, total of 36 mice (Balb/c) of 6 groups (6 mice in each group) were formed: chloroquine group (CG) (50 mg/kg) as malaria reference group, untreated control group (UTCG), O.dubium (OD) (20 mg/kg), O.majorana (OM) (20 mg/kg), S.fruticosa (SF) (20 mg/kg) and L.nobilis (LN) (20 mg/kg). The essential oils were given to mice infected with P.berghei strain orally on 0, 1, 2 and 3rd days (4 times in total). Blood was taken from the tail end of each mouse 24 hours after the last treatment and blood collection was continued every two days until the mice died. Withdrawn blood taken from the mice were prepared as a thin smear and stained with Giemsa. Then, parasitemia percentages in each smear were calculated. As a result of the cytotoxicity tests, cytotoxic activity was not found at 100 µg/ml (20 mg/kg) in all oils except OD essential oil. While the mice receiving chloroquine continued their lives with the disappearance of the parasite on the 6thday, the mice in the UTCG died on the 9th day. The parasitemia rate reached 35% in the OM group on the 23rd day, in the OD group on the 21st day and in the other groups (SF and LN) on the 14th day and the mice have died. In our study, the difference between the life span in all groups was found statistically significant (p≤ 0.001). As a result, the essential oils O.majorana (14 days increase according to UTCG) an endemic plant of Cyprus and O.dubium (12 days increase according to UTCG) which had an antimalarial effect, decreased parasitemia and increased the life span of mice more than two times, indicated that they could be a source for the acquisition of new antimalarial molecules.