Five cases are presented of bilateral simultaneous rupture of the quadriceps tendon and the English literature of six isolated case reports is reviewed. All the patients were men, and most were over 50 years old. The injury often happens in elderly people and there is diagnostic confusion with other causes of inability to use the legs, notably with mild strokes. In three of our five cases there was a delay in diagnosis. The cardinal features are diffuse swelling around the knee, a visible or palpable suprapatellar defect and the inability to lift the straight leg despite a functioning quadriceps and normal activity in all other muscle groups in the leg. In all our patients operative repair was undertaken, followed by six weeks immobilisation in plaster and subsequent physiotherapy. Even late repair was associated with successful rehabilitation of the patient and a return to useful function.