Ceramics are attractive materials for engineering applications involving high temperatures and corrosive chemicals. Here, an inexpensive and reproducible ceramic microfabrication technology was used to fabricate high-density alumina structures for applications in microchemical systems. The new method is based on the gelcasting procedure, but key drying and sintering steps have been adjusted to avoid warpage and cracking of the final structures. Centimeter-scale ceramic structures with submillimeter features can be accurately replicated from an elastomeric mold. Further study of the effect of alumina particle size, D-p, on the smallest achievable and reproducible feature size showed that excellent replication of patterns can be achieved as long as the dimensions of features in the mold are greater than 30D(p) for the range of D-p from 0.3 to 3.0 mu m.