BACKGRUND The direct oral anticoagulants (DOAC) are increasingly used for primary and secondary stroke prophylaxis in atrial fibrillation, although their use in patients with renal failure is problematic. CASE REPORT In an 82-years old female with recurrent strokes and atrial fibrillation, the vitamin-K-antagonist was changed to rivaroxaban because of "unstable international normalized ratio (INR) values". Because of renal failure with a creatinine clearance of 32ml/min, a dosage of rivaroxaban 10mg/d was chosen. Eleven days after initiation of rivaroxaban, she was re-hospitalized because of acute onset of right-sided weakness of the upper and lower limbs. CONCLUSIONS In cases of stroke, renal failure and inadequate anticoagulation it is not useful to change from vitamin-K-antagonists to "low dose" DOAC. Diligent investigations for the cause of INR-instability and continuation of vitamin-K-antagonist therapy seem to be more effective and safer since there is the opportunity of monitoring therapy and to avoid under- as well as over-dosage.