Pleural diseases are among the most common clinical problems encountered in healthcare settings in Malaysia and even worldwide. Most patients presented in a hospital setting with pleural diseases will need pleural aspirations or thoracentesis and chest drains for a variety of reasons. Healthcare providers will often be exposed to patients requiring pleural drainage hence it is important to be aware of safe techniques and procedures of insertion and also maintaining the pleural drainage systems to yield beneficial results. Most often, smaller catheters were deemed to be less effective in view of slower drainage rates and associated with high risk of blockage. However presently , in tertiary hospital settings small bore intercostal chest catheters (SBICC) have become an alternative to large bore intercostal catheters (LBICC). SBICC has been found to be equally effective, less painful and easily tolerated by patients. Hence, proper maintenance of SBICC should be undertaken to reduce rates of occlusion and to yield most benefits from the pleural aspirations procedures. British Thoracic Society in their latest guidelines recommends the use of small bore intercostal chest drain as the first choice in draining pleural effusions. The success of draining pleural effusions with a SBICC has shown variable rates of success among different studies conducted. Most common issues faced are drain blockage and drain dislodgement. There is limited data comparing the use of normal saline flushing versus fibrinolytic drug lock in maintaining patency of small bore intercostal chest drains in draining pleural effusions. This has lead us in conducting this research to compare the rates of partial or complete occlusions among normal saline flush with and without heparin saline lock in maintaining the patency of small bore intercostal chest catheter among patients with pleural diseases in Hospital Canselor Tuanku Muhriz, UKM requiring chest drains insertion.