AbstractTrombocytopenia is related with severity of malaria. Parasitaemia and immune system have important roles for the reactions that occur in malaria infections including thrombocytopenia. Therefore, we conducted a study to determine the association between thrombocytopenia, parasitaemia and cytokines in Plasmodium falciparum and P.vivax. This was a cross-sectional and hospital based study at Mitra Masyarakat Hospital,Timika, Papua, in 2010. Subjects were all age groups with uncomplicated malaria. On admission, characteristics subjects were recorded, parasitaemia was calculated by using microscope, platelets were measured by Hematology analyzer (Sysmex), and cytokines were measured by Multiplex Flow Cytometry Assay (Luminex).Thrombocytopenia was defined if platelet count <150,000/mm . Cytokines were presented in ratio of TNFα/IL10, IFNγ/IL10, and IL12/IL10. The association thrombocytopenia, parasitaemia and cytokines were determined by logistic multivariate analysis. A total 76 subjects were recruited, 51.3% infected with P. falciparum and 48.7% infected with P. vivax infection. The mean age of subjects was 15 (range: 5 – 55) years and 82.9% with thrombocytopenia (platelet range:18958-341123/mm ). The geometric mean of parasitemia was 3393 (43–412503) /mm , while the median of ratios TNFα/IL10, IFN γ/IL10 and IL12/IL10 were 1.05; 0.99; and 0.99, respectively. Bivariate anaylsis showed that trombocytopenia was associated with low level of TNFα/IL10 (p=0.015) and IL12/IL10 (0.020). The multivariate anaysis data also showed a relationship between thrombocytopenia and ratio of TNFα/IL10 with adjusted OR of 7,33 (95%CI: 1,5–35,8), p=0.014. Thrombocytopenia is associated with low ratio of TNFα/IL10 in patients with uncomplicated infection of P. falciparum and P.vivax. AbstrakTrombositopenia berhubungan dengan tingkat keparahan malaria. Parasitemia dan sistem kekebalan tubuh memiliki peran penting pada manifestasi infeksi malaria termasuk trombositopenia. Oleh karenanya penelitian ini bertujuan untuk menentukan hubungan antara trombositopenia, parasitemia, dan sitokin pada Plasmodium falciparum dan P.vivax. Disain studi adalah potong lintang, dilaksanakan di Rumah Sakit Mitra Masyarakat, Timika, Papua pada tahun 2010. Subjek penelitian adalah semua kelompok umur dengan malaria tanpa komplikasi. Pada perekrutan, karakteristik subjek akan dicatat, parasitemia dihitung dengan mikroskop, trombosit diukur dengan Hematology analyzer (Sysmex) dan sitokin diukur dengan Multiplex Flow Cytometry Assay (Luminex). Trombositopenia didefinisikan jika jumlah trombosit < 150.000 mm . Sitokin yang dipaparkan adalah rasio TNFα/IL10, IFNγ/IL10, dan IL12/IL10. Hubungan trombositopenia, parasitemia, dan sitokin ditentukan dengan analisis multivariat logistik. Sebanyak 76 subjek malaria mono-infeksi direkrut, 51,3% terinfeksi P. falciparum dan 48,7% P. vivax. Rata-rata umur subjek adalah 15 (kisaran : 5-55) tahun dan 82,9% dengan trombositopenia (kisaran : 18.958-341.123/ mm 3 3 ). Rerata geometrik parasitemia adalah 3393 (43-412503)/mm , sedangkan median masing–masing rasio TNFα/IL10, IFNγ/IL10 dan IL12/IL10 yaitu 1,05, 0,99; dan 0,99. Analsis bivariat menunjukkan bahwa trombositopenia berhubungan dengan rendahnya tingkat TNFα/IL10 (p = 0,015) dan tingginya rasio IL12/ IL10 (p=0,020). Hasil analisis multivariat menunjukkan adanya hubungan antara trombositopenia dan rasio TNFα/IL10 rendah (< 1,05) dengan OR: 7,33 (95% CI: 1,5-35,8), p = 0,014. Trombositopenia dikaitkan dengan rendahnya rasio TNFα/ IL10 pada pasien infeksi dari P. falciparum dan P. vivax tanpa komplikasi.