OBJECTIVE Ulcerative keratitis is the most serious adverse response associated with contact lens wear. However, some reports of microbial keratitis in the literature may refer to a less severe form of corneal ulceration, which we have termed contact lens induced peripheral ulcers (CLPU). METHODS We present details of 11 cases of CLPU which occurred in clinical trials at our research unit. RESULTS CLPU episodes are characterized by a single, small (< 2 mm diameter) circular lesion in the corneal mid-periphery or periphery, involving a focal loss of the full thickness of the epithelium associated with subepithelial stromal infiltrates. Patient symptoms may include ocular irritation, pain, photophobia, and lacrimation. They are usually associated with the use of hydrogel extended wear contact lenses. The lesions are self-limiting, typically healing within 7 days without treatment. After resolution, a small circular scar remains, which does not affect vision because of its peripheral location. The etiology of CLPU is unclear. In our studies, the incidence of CLPU was similar in conventional (2.9% per patient year) and disposable (2.0% per patient year) hydrogel extended wear, but lower during intermittent extended wear (1.6% per patient year); only one case occurred during daily wear (< 0.5% per patient year). CONCLUSIONS A conservative approach to patient management of all suspected cases of corneal ulceration is encouraged. However, we suggest that future reports of ulcerative keratitis associated with various lens types and wearing schedules should differentiate between potentially devastating microbial keratitis and the relatively innocuous peripheral ulceration described in this paper.