This master's thesis is related to human post-editing (PE) of raw machine translation (MT) output. It aims to identify the particular differences between post-edited versions with and without guidelines. An experiment with participants was carried out to obtain the relevant information. The test group post-edited the raw MT output with post-editing guidelines, while the control group post-editing without guidelines. A third group carried out a human post-editing evaluation. Different aspects were analysed and studied, for example, the time that the participants needed to perform the post-editing task and its relation with the quality of the output, the number and types of changes made during the post-editing phase in both groups and the post-editing effort. We use the PE guidelines proposed by Marian Flanagan and Tina Paulsen in their study of 2014 "Testing post-editing guidelines : how translation trainees interpret them and how to tailor them for translator training purposes".