Bulk pours of cemented tailings sands are used as ground control backfill in underground mines. This paper presents laboratory test data relating design factors, such as cement content, pour pulp density, and curing humidity, to backfill strength. Unconfined strengths were found to increase with increased cement content, increased pulp density, decreased porosity, and decreased curing humidity. Numerical relations between these factors are presented. Test data showing the behaviour of cemented tailings under triaxial compression are also presented. These data indicate that there is a relation between the unconfined strength and the strength envelope defined by c, [Formula: see text] parameters and that either strength can be used in design providing the confining stresses do not approach those required to cause cement bond crushing. Some practical considerations with regard to backfilling with cemented tailings are discussed. Keywords: cemented sand, tailings, strength, curing effects, mine backfill.