Objective:To preliminarily investigate the possible role of prostaglandin D_2(PGD_2) in malaria infections.Methods:Blood and urinary samples(n=120 each) were collected from Thai patients with Plasmodium falciparum(P.falciparum) with moderate(n=26) and high(n=4) parasitemia,patients with Plasmodium vivax(P.vivax)(n=30),patients with fever associated with other infections(n=30),and healthy subjects(n=30).PGD_2 concentrations in plasma and urinary samples of healthy subjects,patients with fever associated with other infections and patients with malaria were determined using Prostaglandin D2-MOX express EIA kit(Cayman Chemical,USA).Results:The possible association between PGD_2 and malaria infections is clearly demonstrated with PGD_2 concentration in urine.The urinary PGD_2 concentrations were relatively high(about 5-fold) in patients with P.falciparum with moderate parasitemia and P.vivax infections compared with other groups.Furthermore,the concentration in patients with P.falciparum with moderate parasitemia and P.vivax infection were significantly higher than that in healthy subjects and patients with fever associated with other infections.Conclusions:Urinary PGD_2 concentrations may offer a more dependable and useful tool for predicting malaria severity.Confirmation is this preliminary finding is required with a larger sample size. Objective: To preliminarily investigate the possible role of prostaglandin D_2 (PGD_2) in malaria infections. Methods: Blood and urinary samples (n = 120 each) were collected from Thai patients with Plasmodium falciparum (P. falciparum) with moderate (n = 26) , patients with fever associated with other infections (n ​​= 30), and healthy subjects (n = 30) .PGD_2 concentrations in plasma and urinary samples of healthy subjects, patients with fever associated with other infections and patients with malaria were determined using Prostaglandin D2-MOX express EIA kit (Cayman Chemical, USA). Results: The possible association between PGD_2 and malaria infections is clearly demonstrated with PGD_2 concentration in urine. The urinary PGD 2 concentrations were relatively high (about 5-fold) in patients with P. falciparum with moderate parasitemia and P. vivax infections compared with other groups. Futurertherm, the concentration in patients with P. falciparum wi th moderate parasitemia and P.vivax infection were significantly higher than that in healthy subjects and patients with fever associated with other infections. Conclusions: Urinary PGD_2 concentrations may offer a more dependable and useful tool for predicting malaria severity. Confirmation is this preliminary finding is required with a larger sample size.