Cleistocactus smaragdiflorus is a species of Cleistocactus found in Bolivia and Argentina.

 Cleistocactus smaragdiflorus grows as a shrub with branched, arched to creeping shoots at the base and reaches heights of growth of up to 1 meter with a diameter of . There are 12 to 14 low ribs present. The 4 to 6 yellowish or brown central spines are 1.5 to 3.5 inches long. The 10 to 34 radial spines that are up to long.

The tubular, straight flowers are erect and long. The flower tube is red to pink. The bracts are little spread. The stylus protrudes slightly from the flower. The spherical fruits reach a diameter of up to .

Distribution: Cleistocactus smaragdiflorus is found among trees and bushes in the dry hills of the Bolivian department of Tarija and the Argentine provinces of Jujuy, Salta, Tucumán and Catamarca at altitudes of 300 to 1,500 meters.

Taxonomy: The first description as Cereus smaragdiflorus was in 1894 by Frédéric Albert Constantin Weber. The plant is name after its emerald green tepals. Nathaniel Lord Britton and Joseph Nelson Rose placed them in the genus Cleistocactus in 1920. Other nomenclature synonyms are Cereus colubrinus var. smaragdiflorus F.A.C. Weber (1894), Cereus baumannii var. smaragdiflorus (F.A.C. Weber) K. Schum. (1897) and Cereus colubrinus var. smaragdiflorus (F.A.C. Weber) Rol.-Goss. (1904).

In the IUCN Red List of Threatened Species, the species is listed as "Least Concern (LC)".