Purpose: To report the unexpected finding of ocular surface neoplasia (OSSN) on conjunctival tissue removed during pterygium surgery and subjected to histopathology analysis. Methods: This is an observational, descriptive retrospective study in which all the samples removed during surgery between 1997 and 2020 with a clinical diagnosis of pterygium were sent for histopathology analysis in which an unexpected OSSN was found. Results: There were 461 cases with a preoperative diagnosis of pterygium, with a mean age of 30.14 ± 10.6 years. In this group, there was an unexpected finding of OSSN in 69 cases (14.96%) of the surgical samples, with a mean age of 46 ± 8.2 years (31.86 ± 12.13). Conclusions: The unexpected coincidence of pterygium and OSSN is frequent, although varies depending on the geographical location. We recommend performing a histopathology analysis on every pterygium removed.