Immune thrombocytopenia (ITP) is a relatively common hematologic disorder manifested by low platelet count due to immune-mediated platelet destruction and/or suppression of platelet production. This study aim was to evaluate characteristics and clinical presentation of adult patients with ITP and exploring the clinical value of platelet antibodies assay in proposed cases in Iranian population. In this prospective case series 46 adult patients with ITP and platelet count of <100 × 10(9)/L, referred to the Taleghani Medical Center, Tehran, Iran between 2007 and 2009 were evaluated. There were 26 females and 20 males (1.3:1) with mean age of 38.9 ± 19.7 years. The platelet autoantibodies were measured by means of indirect platelet suspension immunofluorescence test. According to our results, 7 patients (15.2 %) displayed a positive platelet antibody assay. There was a significant negative correlation between platelet count and antibody level (r = -0 0.59; p < 0.001). Additionally, a positive correlation between platelet count and patients' age (r = 0.302; p = 0.042) was detected. 20 patients (56.5 %) were symptomatic at presentation and the most common bleeding signs were petechia, purpura and epistaxis. Results indicated no significant correlation between increased platelet antibody level and bleeding manifestations except for hematuria (r = 0.435; p = 0.02) and epistaxis (r = 0.382; p = 0.015). Disclosure of platelet autoantibodies and the consequential thrombocytopenia associated to some extent but not completely with the propensity to bleed which necessitates more factors to be evaluated.