Binding studies with the [3H]-nitrendipine were performed in homogenates of chick skeletal myotubes developing in culture. The specific binding data suggested two classes of binding sites with high and low affinities for nitrendipine. No significant changes in the dissociation constants of both high- and low-affinity sites could be detected over the development period studied. The estimated dissociation constant was 0.44 nM for the high-affinity binding site and 25.6 nM for the low-affinity binding site. Both binding sites appeared at an early myotubular stage of development (around 3 days in culture), and displayed rapid increases with age until peaks were reached around 6 days in culture, then began to decrease. These results were discussed taking into account voltage-dependent Ca channels.