Phospholipase C (PLC, EC 3.1.4.11) is an enzyme crucial for the phosphoinositol pathway and whose activity is involved in eukaryotic signal transduction as it generates two second messengers: diacylglycerol (DAG) and inositol 1,4,5-trisphosphate (IP3). There are four major types of phospholipase C named: beta, gamma, delta and the recently discovered epsilon, but this review will focus only on the recent advances for the delta isozymes of PLC. So far, four delta isozymes (named delta1-4) have been discovered and examined. They differ with regard to cellular distribution, activities, biochemical features and involvement in human ailments.