Purpose: To evaluate corneal biomechanics with the Ocular Response Analyzer (ORA; Reichert Ophthalmic Instruments, Depew, NY) after penetrating keratoplasty for keratoconus patients and to compare results with the biomechanical characteristics of normal eyes.Subjects & Methods: This is a prospective comparative clinical study that was conducted on 20 eyes divided into 2 groups: (A) 10 eyes of normal subjects (control group); (B) 10 eyes with manifest keratoconus that had undergone PKP .ORA was performed 2 months postoperatively for all patients. Corneal hysteresis, corneal resistance factor, corneal compensated intraocular pressure, and Goldmann correlated intraocular pressure were measured by ORA. Central corneal thickness was calculated by the integrated handheld ultrasonic pachymeter of the ORA.Results: Both mean corneal hysteresis (CH) and mean corneal resistance factor (CRF) were significantly lower in the Penetrating Keratoplasty group than matched controls.Conclusions: Corneas after Penetrating Keratoplasty have weaker biomechanical properties than normal corneas.