Diploblastic is a condition of the ovum in which there are two primary germinal layers: the ectoderm and endoderm.

Diploblastic organisms are organisms which evolve from such an ovum. Every cell in a diploblastic animal is proximate to its environment, so that all nutritional and waste disposal requirements are handled on a cell-by-cell basis. Compare to triploblastic.

Animals which are diploblastic are radiata.