Blowby emissions contribute a significant part of total hydrocarbon emission by an automobile, but no effort has so far been made in our country to control the same. The diesel engineers have, so far, neglected investigations in this held and the literature available on blowby emissions investigation is very scarce. This paper deals with investigations on the control of blowby emissions in high power turbocharged diesel engine by installing positive crank case ventilation (PCV) system. The lubricating oil mist escaping with blowby gases is also quite significant. Feasibility of recovering this mist by installing in the PCV system a lubricating oil mist separator, designed and fabricated for the purpose has been established. The results obtained clearly show that the blowby emissions can be effectively controlled with the help of PCV system. However, the cross-section area of the PCV pipe has to be adjusted according to the amount of blowby gases and the inflow of ventilating air through the breather. It was possible to separate the lubricating oil mist in the blowby gases and return the lubricating oil back to sump with the use of a mist separator installed in the PCV system. The PCV system and lubricating oil mist separator both can be retrofitted even on engines in service.