ABSTRACT Purpose To evaluate characteristics, etiologies, and outcomes of peripheral ulcerative keratitis (PUK) in Thailand. Methods Retrospective study Results Forty-three eyes from 34 patients were enrolled, with a mean age of 53.44 ± 15.48 years. PUK affected women more than men (1.6:1) and resulted in unilateral lesions more frequently than bilateral lesions (2.8:1). Redness (56.3%) was the most common presenting symptom followed by pain (43.8%) and irritation (40.6%). The three most common etiologies were Mooren’s ulcer (52.9%), rheumatoid arthritis (20.6%), and Graves’ disease (8.8%). Corneal thinning was significantly more common in unilaterality (p = 0.004) and less common when the lesion was located in the superior cornea (p = 0.031). Surgery was also more frequently performed in case of unilateral PUK (p = 0.026). Perforation was observed in 5 eyes (11.6%) and recurrence after treatment was identified in 8 eyes (18.6%). Conclusion Nearly half of PUK cases are associated with several systemic causes. Accordingly, careful physical examination and investigation are important. Unilateral lesions could serve as potential risk factors in identifying patients at risk of thinning and perforation, which could prevent further damage to the eye and vision loss.