Incontinentia pigmenti (IP) is a rare, inherited, multisystem genodermatosis. It is transmitted as an X-linked dominant trait. The disorder is a consequence of mutations in the NEMO gene (Xq28) that completely abolish expression of the NF-kappaB essential modulator. Here we present a female infant of healthy nonconsanguinous, young parents with a clinically evident first phase of IP. PCR analysis of patient's peripheral blood lymphocytes DNA was done for detection of NEMO delta4-10 deletion. Skin changes present at birth appertain to first inflammatory stage. However, a pathohistological feature of the skin biopsy showed second phase of disease. Genetic testing of diseased child revealed delta4-10 in NEMO gene. However, the assumption that the female child has familial IP was rejected as PCR performed on the mother's leukocytes did not record the presence of the same mutation. Moreover, the existence of a healthy male infant of the same mother as well as the lack of any phenotypic signs of the disease in other family members additionally support that IP was not inherited, but it was a consequence of de novo NEMO gene mutation. In conclusion, here we describe a Croatian female with clinical IP phenotype having de novo genomic rearrangements in the NEMO gene.