19-nor-vitamin D analogs having an additional heterocyclic ring connecting the 3.beta.-oxygen and carbon-2 or the 1.alpha.-oxygen and carbon-2 of the A-ring of the analog, and pharmaceutical uses therefore, are described. These compounds exhibit significant activity in mobilization of bone, making them therapeutic agents for the treatment or prophylaxis of osteoporosis, osteomalacia, osteopenia, renal osteodystrophy and hypoparathyroidism.