Abstract : Sotalol is a bêta-blocker and class 3 anti-arrhythmic. Ciprofloxacin is a fluoroquinolone antibiotic used against Gram - germs. Both drugs have a common adverse effect : they increase QT interval with a risk of torsade de pointe. The risk increases even more if other risk factors are present such as old age, female gender, renal failure, high blood pressure and ionic disturbances. Because a long QT interval is not associated with symptoms, only an electrocardiogram can establish the diagnosis. However, it’s not rare that a torsade de pointe will reveal it. We report a clinical case of a long QT interval due to the association of sotalol and ciprofloxacin, which led to a torsade de pointe. Intravenous magnesium sulphate is the recommended treatment if haemodynamic parameters are good. If not, an external electric shock may be needed.