The results of an exploratory investigation on the suitability of periwinkle shells as coarse aggregate for concrete are reported. The tests show that the strength of concrete made with periwinkle shells are limited by the strength of the shells but high enough for structural concrete. The modulus of elasticity and modulus of rupture are low compared with normal gravel concrete. While the strength of reinforced members in direct compression is low, flexural members have satisfactory strength but with larger deformation than normal gravel concrete.