Abstract The aim of this paper is to obtain minimum-cost designs of reinforced concrete structures in conformity with the requirements of the Australian Standard AS3600-1988. The minimum cost structure is such that all its appropriate functional states (stability, strength, serviceability, durability and fire resistance) are within the allowable performance limits. The total cost minimized includes the costs of concrete, reinforcing steel and framework. The minimum-cost problem is formulated as a non-linear programming problem whose solution is attempted by two techniques. Several numerical examples of multi-span beams and of columns are given using a computer package developed in standard FORTRAN77. The sensitivity of the minimum-cost designs to variations in the relative cost of formwork is also studied.