The classic example of a human trait that behaves in a clear Mendelian fashion is human eye color. The gene that controls it exists in two forms: a dominant brown allele and a recessive blue allele. But the genetics of eye color is more complex than typically assumed.  How are green or hazel eyes formed, for example?  And how do blue-eyed couples give rise to brown-eyed offspring, as has been reported?  This case explores the molecular basis of eye color using the story of a blue-eyed couple with a brown-eyed child to explore the possible scenarios that could result in this outcome, emphasizing the link between Mendelian genetics and the underlying molecular basis of the phenotype. The case was designed for second- or third-year biology majors with a background in molecular biology and genetics. In particular, students should have some background in Mendelian genetics and a good understanding of the regulation of gene expression in eukaryotes.