Anti-tumour necrosis factor-α (TNFα) agents are effective in diseases including Crohn's disease but may cause cytopenias. The mechanisms involved in anti-TNFα agent-induced thrombocytopenia are scarce. We report a 73-year-old male with Crohn's disease for which he currently used adalimumab, an anti-TNFα agent. He had received mesalazine and infliximab before the treatment of adalimumab. No comorbidities were present. Routine laboratory tests revealed a deep thrombocytopenia (thrombocytes 24 × 10