INTRODUCTION: This systematic review and meta-analysis evaluated the diagnostic accuracy of MRI-based apparent diffusion coefficient (ADC) and diffusion-weighted imaging (DWI) for differentiating active from inactive perianal fistulas. METHODS: The protocol was registered with the International Prospective Register of Systematic Reviews (PROSPERO) (CRD42024596604). The review included five databases (MEDLINE, Cochrane Library, PubMed, Science Direct, and Google Scholar). Meta-analyses were performed on studies reporting ADC values and other sequences using STATA software with the "Midas" command. RESULTS: Of 21 studies included in the review, 12 were meta-analyzed, encompassing 1007 patients (77.5 % male) with 1092 fistulas and 321 abscesses. Six studies reported ADC values for active vs. inactive fistulas, with a pooled sensitivity of 83 % (95%CI 68-92), specificity of 75 % (95%CI 60-85), and AUC of 0.85 (95%CI 0.81-0.87). Pooled ADC cut-offs ranged from 1.105 to 1.109 × 10⁻³ mm CONCLUSION: ADC alone is inadequate for reliably distinguishing active from inactive fistulas. T2WI combined with DWI offers superior diagnostic performance, surpassing contrast-enhanced T1WI, and is promising for non-invasive evaluation of perianal fistulas. However, several limitations, such as moderate to high risk of bias and heterogeneity, may bias this conclusion. IMPLICATIONS FOR PRACTICE: T2WI + DWI could become the standard for assessing perianal fistulas, avoiding contrast agents, and benefiting patients contraindicated for Gadolinium-based contrast media. Variability and potential bias across studies warrant further research.