The metabolic syndrome (MetS) is a cluster of coexisting cardiovascular risk factors. The role of specific dietary fats was reemphasized by dietary recommendations. This systematic review aims to assess evidence for the effect of dietary fat intake on MetS occurrence and reversion in adults. The MEDLINE database was used to search the existing literature. We included observational studies that analyzed dietary fat intake in adults with MetS and clinical trials that compared the effects of different dietary fat diets on MetS and/or its components. Thirty articles were selected (14 observational and 16 clinical trials), and we included information of dietary fat and fatty acids as well as MetS, body mass index, cholesterol, hypertension, and diabetes in adults. SFA intake was found to be positively associated with MetS components. Most of the observational reviewed studies found beneficial associations between MUFA and PUFA (including n-3 and n-6 subtypes) intake and MetS components. Clinical trials also supported the benefits of MUFA- or PUFA-enriched diets (including low-fat diets) in reducing MetS. The effects of dietary SFAs on MetS will be influenced by other specific nutrients. Replacement of SFA by MUFA and PUFA has been associated with a decrease in MetS. Dietary recommendations should emphasize on different qualities of fat intake, not only to reduce total fat intake, to obtain health benefits in adults.