Thirty five patients, twenty nine men and six women with a mean age of twenty six and suffering from a pyothorax 23% or a pyopneumothorax 77% of whom 41% had a bronchopleural fistula on chronic evolution (greater than one month before drainage), had been treated using drainage and lavage with iodised polyvinylpyrrolidine without local or general antibiotics. This treatment enabled thirty four patients to be cured with some moderate radiological sequelae, a 50% restitution "ad integrum". The importance of the sequelae was correlated with increased aged (P less than 0.001), a delay before drainage (P less than 0.001) and a prolonged duration of drainage (P less than 0.01), to multiple organisms (P less than 0.01) and the presence of a pneumothorax (P less than 0.02) and to a tuberculous origin of the effusion (P less than 0.01). These two latter factors were the cause of a prolongation of the duration of drainage (P less than 0.01). Tuberculous patients who on average were older (P less than 0.05) and had a prolonged period of drainage (P less than 0.01) presented with major immediate radiological sequelae (P less than 0.01). In conclusion the technique of drainage using iodised polyvinylpyrrolidine gave excellent results in cases of non-tuberculous pyothorax in young subjects, but gave less impressive results in subjects suffering from tuberculosis, because of the significant radiological sequelae.