Cyclical　thrombocytopenia　(CT)　is　a　rare　hematological　disease　characterized　by　periodic　oscillations　in　circulating　platelet　counts.　In　almost　all　CF　patients,　other　cell　lines　show　no　sign　of　oscillation,　but　recently　a　CT　patient　was　reported　with　significant　oscillations　in　circulating　neutrophils　(in　the　same　period　as　the　platelets).　In　this　paper,　we　attempt　to　understand　this　phenomenon　through　a　previously　published　model　of　human　hematopoiesis.　We　have　investigated　a　variety　of　possible　oscillation　patterns　that　may　appear　when　alterations　occur　in　the　control　parameters　in　the　platelet　regulatory　dynamics.　Our　results　indicate　that　the　platelet　maturation　time　and　the　differentiation　rate　from　hematopoietic　stem　cells　(HSCs)　into　the　platelet　cell　line　play　important　roles　in　the　emergence　of　various　types　of　CT　like　oscillations.　Moreover,　we　find　different　oscillation　patterns,　including　CT　and　cyclical　neutropenia　like　oscillations,　with　certain　parameter　values　in　the　platelet　compartment.　A　bifurcation　analysis　revealed　the　different　origins　of　these　oscillation　patterns.　We　also　identified　bistable　dynamics　which　indicate　the　potential　importance　of　system　history　in　the　treatment　of　these　diseases.　Together,　these　results　demonstrate　the　possible　origins　for　various　oscillation　patterns　dependent　on　alterations　in　the　platelet　cell　line　control　mechanisms.　One　of　the　important　origins　may　be　related　to　the　regulation　of　apoptosis　in　platelet　precursors.　Crown　Copyright　(C)　2018　Published　by　Elsevier　Ltd.　All　rights　reserved.