Abstract Background Hepatosplenic schistosomiasis mansoni (HS) is associated with thrombocytopenia. Accurate platelet counts are required for identification and management of HS patients. EDTA-dependent pseudothrombocytopenia (EDTA-PTCP) is an in vitro phenomenon of anticoagulant-activated platelet agglutination resulting in low platelet counts by automated methods. The prevalence of EDTA-PCTP in schistosomiasis is unknown and only one case has been described. Our aims were to determine the prevalence of EDTA-PTCP in HS and evaluate alternative methods to overcome this analytical error. Methods Blood samples from 56 HS patients and 56 healthy volunteers were collected, and platelet counts were obtained using standard microscopy and automated (electric impedance) methods. Automated platelet counts and the presence of platelet clumps in blood smears were evaluated in samples collected in EDTA or sodium citrate tubes 20 and 180 min after blood collection. Results EDTA-PTCP was more frequent in HS patients than healthy volunteers (8.92% vs 0.00%, p<0.0285). Platelet clumps and PTCP were also observed in samples collected in sodium citrate tubes, refuting its use as an alternative method. Conclusions Automated platelet counts in blood samples from HS patients should be performed right after blood collection in EDTA tubes and verified by manual counts in blood smears.