Colloidal CdTe quantum wires are reported having ensemble photoluminescence efficiencies as high as 25% under low excitation power densities. High photoluminescence efficiencies. are achieved by formation of a monolayer Cds shell on the CdTe quantum wires. Like other semiconductor nanowires, the CdTe quantum Wires may contain frequent wurtzite-zinc-blende structural alternations along their lengths.' The present results demonstrate that the optical properties, emission peak shape and photoluminescence efficiencies, are independent of the presence or absence of such structural alternations.