A 52-year-old man presented with a two month history of left sided chest pains related to a pleurisy which showed an 18 per cent eosinophilia on pleural aspiration. He was hospitalised one month later and at that stage was very dyspnoeic and there was a bilateral pleural effusion associated with a significant pericardial effusion causing compression. A pleuro-pericardial drainage eased the patient's symptoms. The pleural fluid showed an 87 per cent lymphocytosis and a complete diagnostic work up was negative thus a diagnosis of idiopathic eosinophilic pleurisy with an associated pericarditis was made. Steroid therapy was instituted using half a milligram per kilo and this led to a rapid functional improvement and no recurrence of the effusions were noted. The treatment was progressively stepped down over the next five months and the patient's condition was satisfactory without any recurrence at nine months.