Protein kinase C family consists of 11 isoforms, classified into 3 categories according to their structure and mechanisms of activation. These isoenzymes are involved in processes, which maintain intracellular homeostasis. Alterations in activity, amount or distribution of protein kinase C (PKC) isoenzymes may cause cellular proliferation or induce apoptosis. We have studied and compared the expression levels of several PKC isoforms in benign prostatic hyperplasia (BPH) and prostate cancer (PCa). These are PKCs alpha (alpha), beta (beta), delta (delta), epsilon (epsilon), zeta (zeta), eta (eta), which have been detected as major isoforms in prostate tissue. Paraffin sections of 25 benign prostatic hyperplasia (BPH) and 25 of prostatic carcinoma (PCa) were examined for expression of PKC alpha, beta, delta, epsilon, zeta, and eta. Expression of PKC beta was examined in additional 3 BPH and 3 PCa using Western blot analysis. We found a significant high level of expression of PKC isoforms alpha, beta, epsilon and eta in PCa compared to BPH (p<0.01). Using backward logistic regression, we found changes in PKC epsilon expression to be most significant between malignant compared to benign tumor tissue specimens. Immunostaining for PKCs alpha, beta and eta in addition to PKC epsilon may aid in distinguishing between benign and malignant prostatic disease.