Background: Dietary Fibre (DF) has been part of human diet since ever, and its benefits for the human health have been well established and scientifically confirmed. However, it is important to study to what extent people are aware of those benefits.Objective: Having in mind the importance of DF the present work was undertaken to study the level of knowledge of people residing in Portugal about the health effects related to DF. Methods: A descriptive cross-sectional study was undertaken on a non-probabilistic sample of 382 adult participants. Descriptive statistics were used together with some inferential tests, all using the software SPSS and considering a level of significance of 5%. Results: The results allowed concluding that people were differently informed about the effects of DF in preventing and/or treating various diseases, being constipation the most recognized, followed in decreasing order by obesity, bowel cancer, cholesterol, cardiovascular diseases, diabetes and breast cancer. The results also showed that significant differences were encountered between age groups for most of the diseases evaluated, but not between genders, levels of education or living environments. Conclusion: Generally, it was concluded that the participants in this study were relatively well informed about the roles of DF in preventing and/or treating several diseases.