We report the first case of junctional tachycardia in a patient treated with paclitaxel. A 60-year-old woman with advanced breast cancer received palliative chemotherapy with 22.5 mg/m2/day paclitaxel over a 7 day continuous infusion as part of an investigational regimen. Although the patient had no previous or current history of cardiac disease, she developed severe symptomatic tachycardia, which occurred toward the end of the second and third courses. Anti-arrhythmic medication was prescribed and electrocardiographic records identified electric patterns of junctional tachycardia. Given both the physiopathology of arrhythmic disorders and pharmacokinetics of the patient, this case report supports the hypothesis that automatic junctional rhythm after severe asymptomatic conduction block rather than direct primary toxicity on myocytes caused this toxicity.