Background: Psoriasis significantly impacts patients' physical and mental well-being, leading to functional limitations in various domains. Understanding the link between disease severity and functional disabilities is crucial for optimizing treatment strategies and improving patient outcomes. Aim: was to explore the relation between psoriasis severity and functional disability among patients with psoriasis. Design: A correlation and cross-sectional research design was employed to achieve the current study aim. Setting: The current study was carried out at Kasr Al-Ainy Psoriasis Unit and Dermatology Department. Sample: A purposive sample of 150 participants was recruited for the study. Tools:  three tools were used by the researchers for data collection; Tool (I): Participants' Socio-Demographic Characteristics and Medical Related Data form; Tool (II) Psoriasis Area and Severity Index (PASI) and Tool (III) Psoriasis Disability Index (PDI). Results: Mean age of the current study participants were (38.9±7.85), (38%) of participants had severe PASI score and (52.6%) of them had severe PDI score. the total PDI had a positive strong correlation with PASI score (r=0.751, p<0.005). Conclusion: Based on the results of the current study, there was a significant correlation between all components of PDI and PASI scores particularly the daily activities and work; in addition, the total PDI score had a positive strong correlation with PASI score. Recommendations: Development of evidence-based guidelines for managing functional limitations in psoriasis patients is crucial.