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INTRODUCTION Treatment of venous thromboembolism (VTE) in cancer patients with thrombocytopenia is challenging due to perceived higher risk of bleeding. MATERIAL AND METHODS We used the RIETE registry to compare the 10- and 30-day outcomes in cancer patients with acute VTE, according to platelet count at baseline. RESULTS As of December 2018, 15,337 cancer patients with VTE were included: 166 (1.1%) had <50 × 109 platelets/L (severe thrombocytopenia), 711 (4.6%) had 50-99 × 109/L (mild thrombocytopenia) and 14,460 (94.3%) had ≥100 × 109/L (normal count). Most patients in all subgroups received initial therapy with low-molecular-weight heparin (LMWH), but 62% of those with severe thrombocytopenia received <150 IU/kg/day LMWH, 42% received <100 IU/kg/day. The mortality rate progressively decreased with increasing platelet counts (12%, 9.4% and 3.3% respectively at 10 days, 27%, 18% and 9.4% at 30 days), but the major bleeding rates did not (1.2%, 2.5% and 1.3% respectively at 10 days, 2.4%, 4.4% and 2.2% at 30 days). On multivariable analysis, patients with severe thrombocytopenia had a similar risk for major bleeding at 10 days (OR 0.84; 95%CI 0.20-3.49) and at 30 days (OR 0.90; 95%CI 0.32-2.49), but those with mild thrombocytopenia were at increased risk both at 10 days (OR 2.11; 95%CI 1.27-3.49) and at 30 days (OR 1.91; 95%CI 1.29-2.84). CONCLUSIONS Cancer patients with acute VTE and baseline thrombocytopenia often receive initial lower-than recommended doses of LMWH. Although caution is required, this practice seems to be safe in patients with severe thrombocytopenia. Nonetheless, there was an inverse correlation between baseline platelet count and mortality.