INTRODUCTION: Hereditary leukonychia is a rare genetic nail disorder characterized by whitening of the nail plate, which is sometimes due to mutations in the CASE PRESENTATION: A 39-year-old Kuwaiti male with autosomal recessive variant of PLCδ1-related non-syndromic leukonychia affecting nine fingernails presented for treatment because he was socially stigmatized. Treatment with 30% glycolic acid chemical peel was ineffective. Because there is evidence suggesting a link between PLCδ1-related hereditary leukonychia and abnormal keratinization, we hypothesized that injection of steroids into the nail matrix, which could inhibit keratinocyte activity and reduce nail matrix inflammation, may be an effective treatment. Following treatment with intramatricial triamcinolone, the patient experienced complete resolution of leukonychia in five fingernails and partial improvement in the remaining four. CONCLUSION: We present a case of successful treatment of hereditary leukonychia due to a phospholipase C δ-1 gene mutation with intramatricial triamcinolone. This case highlights the potential of this treatment approach for leukonychia and warrants further investigation in larger cohort studies.