201 adults with non-specific pleural empyema (58 women, 143 men) had suction drainage. Most of the patients were aged 61-70 years. In the 47 patients who had not had antibiotic therapy before admission the main causal micro-organisms were staphylococci, pneumococci and streptococci; in the 149, who had had antibiotic therapy outside, micro-organisms such as Pseudomonas, Esch. coli and Proteus predominated. Suction drainage had to be kept up for a remarkably long time: for 4-8 weeks in 36% of the cases and for more than 8 weeks in 8%. 31 patients died, but only 17 of them as a direct result of the pleural empyema. They had all been "high risk" cases on account of age (average 67.7 years), type of bacteria (59%), serious primary or complicating disease (59%), duration of the pleural empyema (76%). Suction drainage succeeded in 140 patients in clearing the infection; but marked adhesions were demonstrable in 27% of the patients when they were discharged from hospital.