The objective of this study was to evaluate the quality of Portuguese obesity websites. A cross-sectional, quantitative and observational study was designed. The evaluation of 127 sites found using the Google in “Advanced Search” option “pages in Portuguese”, country “Portugal” was performed. The quality criteria used in this study resulted from the merger/adaptation from several authors previously published. The information on obesity was evaluated according to the Scottish Intercollegiate Guidelines Network: Management of Obesity, a National Clinical Guideline, 2010. The quality criteria most mentioned in the websites, were the purpose (80.3%) and authority (73.2%). On the other hand, the editorial review (7.9%) and references (15.7%) were mentioned in the narrowest websites. The websites analyzed had a mean quality score of 5.2 points (± 2.1) out of 11. A significant correlation was found between the score of information on obesity and quality score for adults group (0.282) and both ages group (0.437). In Portugal, the websites that provide information on obesity had, generally, a low quality score.