Elastogenesis in the ligamentum nuchae of the fetal calf commences with the extracellular deposition of hollow‐appearing filaments, 130 Å in diameter, showing a banding pattern consisting of alternating segments, 50 Å and 130 Å long, respectively. Similar filaments are found in the crude extract of the ligament. Mature elastin forms within these masses of filaments and displays an internal, branching tangle of 30 Å filaments. Elastogenesis is accompanied by a high level of cellular activity involving acanthosomes, which have been interpreted as a mechanism of secretion of protein‐polysaccharide complexes.