Precipitation and deposition of heavy organic materials such as asphaltene inside reservoirs, processing and transportation facilities is a major concern in the oil industry. Asphaltene precipitation is one the most common problem in many reservoirs and unfortunately may lead to many safety operational issues that in end affect's oil recovery which assumes to be a major economical loss. The precipitation and deposition of asphaltene in porous media and their interactions with rock and fluids is a complex phenomenon which begs to be investigated under reservoir conditions. As yet, there have been many studies conducted on asphaltene precipitation but majority of them focused on determining precipitation onset point. It is believed, the first step in attempting to find an engineering solution to this deposition problem is to identify the conditions at which asphaltene precipitation takes place initially and conditions after that influences deposition. This paper presents an assessment of aspects that influences asphaltene precipitation and deposition. This research, attempts to understand the mechanism of asphaltene precipitation and deposition, parameters affecting the precipitation and deposition process, the effect of asphaltene precipitation and deposition on oil reservoir characteristics and performance. In addition, the research involves examining the existing thermodynamic models of asphaltene precipitation and deposition in porous media, reversibility of asphaltene precipitation and deposition, asphaltene deposition removal methods, and modelling and simulation of asphaltene by conventional simulators. Since this study is a comprehensive summary of the mentioned topics and contains all the essential information of asphaltene and its precipitation process, it therefore can be used as a reference for further exploration of this specialized field.The probability of asphaltene precipitation and deposition occurring during any EOR techniques and its effects on reservoir performance should be anticipated at earlier stages of any development project. Also it is believed that through a more comprehensive understanding of the mechanisms that lead to deposition in the first place; asphaltenes deposition if cannot be prevented fully may at least be controlled and managed. Copyright 2011, Society of Petroleum Engineers.