Degradation of the environment is nowadays believed to be the most alarming problem that needs to be solved. Global warming and environmental pollution are predicted to cause a catastrophic chain reaction leading to species extinction, mass emigration due to rising sea levels and global crisis. The only solution suggested by international organizations is the immediate reduction of greenhouse gases and other harmful substances. Marine transportation harmful substances into the atmosphere are recognized to be a significant source of global atmospheric pollution. Despite the high efficiency of marine diesel engines, their impact on the environment is considerable. Due to environmentally friendly policies, modern engines concerns about not only efficiency but also mainly about s aspects. This article analyses and compares marine s exhaust gases reduction methods. Especially the most harmful substances emitted by ships were taken into consideration. The article presents the most crucial law regulations of harmful substances to the atmosphere, pointing at actual and possible future implementations. The most complex methods allowing meeting the latest limits were presented. Pros and cons of available control methods were thoroughly described and methods were compared. The most adequate methods form the effectiveness and economical point of view was pointed out.