Immunotherapy has advanced the treatment of solid organ malignancies. Although generally well tolerated, treatment with immune checkpoint inhibitors can be complicated by immune-related adverse events, some of which are relatively uncommon. We report the first case of gingival linear immunoglobulin A disease related to treatment with an antiprogrammed cell death protein 1 antibody. A 73-year-old male with advanced non-small cell lung cancer achieved a durable response to nivolumab monotherapy. After 1 year of treatment, he developed gingival swelling and pain. Biopsy revealed linear immunoglobulin A disease of the gingiva which was effectively treated with systemic steroids. Ongoing vigilance for immune-mediated toxicity is paramount during and after treatment with immune checkpoint inhibitors.