PURPOSE: To verify the universal nature of the phonological processing deficit hypothesis for dyslexia, since the most influential studies on the topic were conducted in children or adults speakers of English. RESEARCH STRATEGY: A systematic review was designed, conducted and analyzed using PubMed, Science Direct, and SciELO databases. SELECTION CRITERIA: The literature search was conducted using the terms "phonological processing" AND "dyslexia" in publications of the last ten years (2004-2014). DATA ANALYSIS: Following screening of (a) titles and abstracts and (b) full papers, 187 articles were identified as meeting the pre-established inclusion criteria. RESULTS: The phonological processing deficit hypothesis was explored in studies involving several languages. More importantly, we identify studies in all types of writing systems such as ideographic, syllabic and logographic, as well as alphabetic orthography, with different levels of orthography-phonology consistency. CONCLUSION: The phonological processing hypothesis was considered as a valid explanation to dyslexia, in a wide variety of spoken languages and writing systems.