Purpose: The purpose of this study was to compare cutaneous surface parameters in lesional and non-lesional skin of psoriatic patients and in corresponding areas of control subjects. Methods: Sixty-six psoriatic patients (of any grade of severity, with or without arthritis, without any therapy other than systemic biologic drugs) and 28 healthy controls were enrolled in this observational, case control study. Exclusion criteria were current or past sebo-psoriasis and seborrheic dermatitis, pustular or erithrodermic psoriasis; treatment with immune-suppressive agents, retinoids, or ultraviolet phototherapy in the last 6 months; topical treatment in the last 2 weeks. Corneometry, sebumetry, and pHmetry were evaluated on non-lesional skin of forehead, cheek, chin and volar region of forearm, and on a psoriatic plaque (on elbow or neighboring areas); in controls, the same areas were considered. Results: Corneometry values were significantly lower in psoriatic plaques vs. elbows of controls. Sebumetry showed significantly higher values in non-lesional forearm skin and plaques of psoriatic patients vs. corresponding areas of controls. pH was significantly lower in all areas in psoriasis. No differences were found between patients treated or not with biologics and with or without arthritis. Conclusion: Evaluating surface skin parameters in psoriasis is useful to better understand the etiopathogenic mechanism and could suggest new therapeutic approaches.