Abstract Background There have been few published reports on severe Plasmodium falciparum and Plasmodium vivax malaria among adults in Africa. Methods Clinical pattern/manifestations of severe P. falciparum and P. vivax (according to World Health Organization 2000 criteria) were described in adult patients admitted to Kassala Hospital, eastern Sudan. Results A total of 139 adult patients (80 males, 57.6%) with a mean (SD) age of 37.2 (1.5) years presented with severe P. falciparum (113, 81.3%) or P. vivax (26, 18.7%) malaria. Manifestations among the 139 patients included hypotension (38, 27.3%), cerebral malaria (23, 16.5%), repeated convulsions (18, 13.0%), hypoglycaemia (15, 10.8%), hyperparasitaemia (14, 10.1%), jaundice (14, 10.1%), severe anaemia (10, 7.2%), bleeding (six, 4.3%), renal impairment (one, 0.7%) and more than one criteria (27, 19.4%). While the geometric mean of the parasite count was significantly higher in patients with severe P. vivax than with severe P. falciparum malaria (5,934.2 vs 13,906.6 asexual stage parasitaemia per μL, p = 0.013), the different disease manifestations were not significantly different between patients with P. falciparum or P. vivax malaria. Three patients (2.2%) died due to severe P. falciparum malaria. One had cerebral malaria, the second had renal impairment, jaundice and hypoglycaemia, and the third had repeated convulsions and hypotension. Conclusions Severe malaria due to P. falciparum and P. vivax malaria is an existing entity among adults in eastern Sudan. Patients with severe P. falciparum and P. vivax develop similar disease manifestations.