Sucker rod pumps are the most used type of artificial lift system worldwide. Although it is one of the most sophisticated and most reliable system it is also subjected to failure. Failure in sucker rod pumps often occur within the sucker rod string evoked by misalignment of the downhole string resulting in high friction and wear between the string and tubing. To reduce abrasion of the deployed sucker rods, couplings and tubing, rod guides are installed at certain intervals along the string. Those rod guides are typically made out of polymers featuring a slightly less diameter than the tubing string. According to an Austrian oil company, it is common practice that sucker rod guides are replaced after a certain predefined time interval without knowing the actual condition of the rod guide. This thesis will address the friction and wear behaviour of sucker rod guides deployed in a horizontal wellbore. The investigation will be conducted utilizing a custom made experiment to get information about the wear rate per stroke length. The engineered test facility is capable of simulating different temperatures, media and stroke rates. Furthermore the coefficient of friction between the nylon rod guide and steel tubing will be determined. The outcome of this thesis will give information about the coefficient of friction and wear rate of rod guides under certain downhole conditions. Parameters determined in this thesis will serve as reference for any petroleum engineer dealing with sucker rod guides to be able to give a better rod guide lifetime estimation according to present downhole conditions.