With an increasing number of Internet research in general, the number of qualitative Internet studies has recently increased. Online forums are one of the most frequently used qualitative Internet research methods. Despite an increasing number of online forum studies, very few articles have been written to provide practical guidelines to conduct an online forum as a qualitative research method. In this article, practical guidelines in using an online forum as a qualitative research method are proposed based on three previous online forum studies. First, the three studies are concisely described. Practical guidelines are proposed based on nine idea categories related to issues in the three studies: (a) a fit with research purpose and questions, (b) logistics, (c) electronic versus conventional informed consent process, (d) structure and functionality of online forums, (e) interdisciplinary team, (f) screening methods, (g) languages, (h) data analysis methods, and (i) getting participants' feedback.