Background: Evaluation of the prevalence of PsA in patients with psoriasis has ranged broadly from 7% to 48%. This variability is related in part to the definition of the disorder, source of patients, and geographic variation. Aim: This work aims to determine the prevalence of undiagnosed Psoriatic Arthritis (PsA) among psoriasis patients. Materials and Methods: A systematic search was performed over different medical databases to identify Dermatology studies, which studied the prevalence of undiagnosed PsA among psoriasis patients. Using the meta-analysis process, either with fixed or random-effects models, we conducted a meta-analysis on overall PsA prevalence as a primary outcome, and on psoriasis severity in PsA patients as a secondary outcome, which was assessed via Psoriasis Area and Severity Index (PASI). Results: Ten studies were identified involving 97762 psoriasis patients. The metaanalysis process revealed that the estimated pooled prevalence of undiagnosed PsA among psoriasis patients was (13.76%) (95% CI 6.689 to 22.856). We also found a highly significant increase in mean PASI, in PsA patients compared to the remaining dermal psoriasis (p<0.0001). Conclusion: To conclude, the findings are consistent with a low prevalence of PsA among patients with psoriasis and confirm a high percentage of undiagnosed cases with active arthritis among PsA patients in dermatologist’s office. Dermatologists should screen for PsA in their patients, especially those with risk characteristics and early signs.