Problem under Study – Pleural Effusion is a common cause of morbidity/mortality in our daily clinical practice. There are several causes of Pleural Effusion. Whereas most medically related causes require treatment directed mainly at the primary cause, others require in addition some form of surgical intervention. Objective of the Study – To find out the common causes of surgically important pleural effusion in the National Hospital Abuja Nigeria, and also the contemporary methods of diagnosis , therapy and outcome of such. Methodology – All cases of Pleural Effusion requiring some form of surgical intervention , by way of tube thoracostomy drainage at some point in their management were sampled over a one year period spanning between February 2005 to February 2006 in a prospective fashion. Relevant clinical data including clinical symptoms and signs, radiological findings, results of pleural fluid analysis ,primary disease condition, treatments directed at both the primary pathology as well as the effusion , the common complications observed during treatment and the outcome of these treatments recorded at 6 months re-evaluation were all recorded in a proforma. Statistical analysis of data was done with EPI-INFO soft ware and presented in form of pie charts, bar charts, histogram and tables. Results – Of the 86 cases of surgically important pleural effusion sampled, the commonest presentation was dyspnoea (100%) and dullness to percussion on the affected hemithorax(100%). Thoracentasis yielded straw coloured fluid in (54.7%), sero-sanguinous in (27.9%), turbid/purulent in (16.3%) and chyle in (1.2%) only. The commonest radiological feature was the meniscus sign in addition to the other radiological features of the primary pathology. Chemistry analysis of the aspirate confirmed it to be exudative effusion in 100% of cases. Neoplastic disease was found in 35 cases (40.7%), Pulmonary tuberculosis in 32 cases (37.2%) and Pneumonia in 19 cases (22.1%). The commonest cause of malignant effusion was found to be Breast Carcinoma which was recorded in 65.7% of these. Others were soft tissue sarcoma (11%), lung carcinoma (11.4%), intra-abdominal carcinoma (8.6%), parotid carcinoma (2.9%). Most patients had tube thoracostomy drainage of the effusion in addition to the treatment of the primary disease condition. Concerning outcome of treatment, 71% of those with malignant effusion were dead at 6 months and indeed recorded the worst prognosis amongst the causes of primary pathology. The commonest complication observed during treatment was premature dislodgement of the chest tube. Discussion/Conclusion – Neoplastic disease was the leading cause of surgically important pleural effusion from this study with Breast carcinoma contributing the highest quota. It also represents the worst prognosis as well above 2/3 of all such cases were dead at 6 months. Para-pneumonic effusions had the best outcome as 88% of them did not show any evidence of the disease or any complication arising there from at 6 months reevaluation. This may be related to availability of appropriate antibiotics and early exhibition of such. Tuberculous effusions had a far better prognosis than malignant ones, but not as good as the para-pneumonic ones. Application of diagnostic armaments and early diagnosis is important in the eventual outcome of treatment of pleural effusions.