Objective:To investigate the levels of serum Cortisol in patients with uncomplicated Plasmodium falciparum(P.falciparum) malaria in an area of unstable malaria transmission in eastern Sudan. Methods:The concentrations of Cortisol were measured in sera of 25 patients with uncomplicated P.fylciparum malaria(at presentation,24 h and 7 d later) and 25 healthy volunteers using radioimmunoassay gamma counter.Results:There was no significant difference in mean(SD) of total Cortisol levels in patients with malaria in comparison with the control group;602.2(369.6) vs. 449.2(311.7) ng/mL,P=0.12.In patients with uncomplicated P.falciparum malaria,the mean(SD) presenting Cortisol levels were significantly higher in comparison to the levels on day 7;602.2 (369.6) vs.373.6(139.1) ng/mL,P=0.009.In the patients with uncomplicated P.falciparum malaria (on presentation) Cortisol levels were not correlated with initial temperature or the presenting parasitaemia.Conclusions:Thus,Cortisol levels were not significantly different between the patients and the controls.