A 35-year-old Greek woman (Fitzpatrick Skin Type IV) presented to our clinic 4 months after the delivery of her first child with nail changes that were first noted during pregnancy. During the 12th week of pregnancy, homogenous dark brown streaks appeared first on the nails of her right second and third fingers (Figure 1a, b) and later on her right fourth toenail (Figure 2a). During the following weeks, she developed similar changes on the second and fourth toenails (Figure 2b). The streaks were uniformly brown, with distinct margins and width of 2-5 mm. There was no pigmentation in the periungual skin (Hutchinson sign) of the affected nails. The direct microscopic examination, cultures, and polymerase chain reaction (PCR) were negative for dermatophytes. The nail changes had not resolved after delivery. Throughout the gestational period, she had developed alveolar hyperpigmentation, but no other changes including the lack of multiple lentigines. During her pregnancy, she had taken calcium supplements from the 8th week until delivery, magnesium and iron supplements throughout pregnancy, as well as progesterone 100 mg daily (Utrogestan®, Besins Healthcare Ltd) from the 8th week through the 12th week. She was otherwise healthy and had no previous pigmentation disorders, chronic diseases, or any other pregnancy complications. There was no family history of pigmentation disorders.