The study investigated use of internet in sex education among undergraduate students: a case study in university of Port Harcourt. A sample of 300 undergraduate students was used for the study from 12 departments using sample size of 300 was drawn using two sampling techniques: cluster sampling technique and simple random sampling technique. Three research questions were answered. The instrument for the study was a questionnaire tagged Use of Internet in Sex Education (UISE). The data collected were analyzed with mean and standard deviation to answer the research questions one and two while percentage is used to answer research question three. From the analysis, it was found out that there is effectiveness in using internet for sex education among undergraduate students. The findings revealed that there is availability of internet for sex education among undergraduate students in university of Port Harcourt. Finally, respondents agreed that social media is the best suited channel for sex education among undergraduate students in university of Port Harcourt. Based on the findings, it was recommended that Internet sex education should be introduced at all level of the educational systems in Nigeria, this will to a large extent expose undergraduate students to the dangers associated with certain dangerous sexual behaviour which is occasioned by exposure to the social media.