In this study, we determined the expression of protein kinase C (PKC) isoforms during trauma-induced decidualization. The findings revealed that at least five PKC isoforms (alpha, delta, zeta, iota and lambda) were present in both control and decidualized tissues. After trauma-stimulation, PKC alpha was down-modulated in the deciduomata but not in the myometrium. Down-modulation was compatible with the increase in cell mitosis which reached a maximum at 2-3 days. On the other hand, PKC zeta was not down-modulated. It was increased both in the deciduomata and myometrium, and paralleled the frequency of decidual cell mitosis. The PKC isoforms of delta, iota and lambda were also increased, but they were associated with the depression of cell mitosis. Therefore, these findings suggested that the variable expression of PKC isoforms in trauma-induced decidualizing tissue in pseudopregnant rats may be involved in the modulation of decidual cell growth.