High-flux hemodialysis is the extracorporeal treatment of choice for various life threatening intoxications. Most published reports support the use of hemoperfusion in the context of severe theophylline poisoning, but the technique is limited by its significant side-effects. We present a potentially life threatening theophylline overdose treated with hemodialysis in a pregnant patient. For the first time the amount of theophylline removed was measured in the total collected spent dialysate, after a 3.75 hour hemodialysis and an 8 hour extended dialysis.