Purpose. Rash occurs in >50% of patients prescribed epidermal growth factor receptor (EGFR) inhibitors. This study was undertaken to determine whether sunscreen prevents or mitigates these rashes. Methods. This placebo-controlled, double-blinded trial enrolled rash-free patients starting an EGFR inhibitor. Patients were randomly assigned to sunscreen with a sun protection factor of 60 applied twice a day for 28 days versus placebo. They were then monitored for rash and quality of life (Skindex-16) during the 4-week intervention and for an additional 4 weeks. Results. Fifty-four patients received sunscreen, and 56 received placebo; the arms were balanced at baseline. During the 4-week intervention, physician-reported rash occurred in 38 (78%) and 39 (80%) sunscreentreated and placebo-exposed patients, respectively (p = 1.00); no significant differences in rash rates emerged over the additional 4 weeks. There were no significant differences in rash severity, and patient-reported outcomes of rash yielded similar conclusions. Adjustment for sun intensity by geographical zone, season, and use of photosensitivity medications did not yield a significant difference in rash across study arms (p =.20). Quality of life scores declined but remained comparable between arms. Conclusions. Sunscreen, as prescribed in this trial, did not prevent or attenuate EGFR inhibitor-induced rash.