Ertapenem is a β-lactam antibiotic that has a broad spectrum of anti-microbial coverage. Hematological adverse events like thrombocytosis, neutropenia, and neutropenia are infrequent. Here we report a rare case of drug-induced thrombocytosis in a 68-year-old female, who was treated with ertapenem for the diagnosis of complicated abdominal infection. This case emphasizes that any patient with thrombocytosis should be assessed with a careful and detailed history with consideration for possible drug side effects.