Clinical and morphological studies were undertaken to examine 168 patients with glioblastomas of the cerebral hemispheres. They revealed that the longevity of the hemispheres was substantially influenced by three immunobiological criteria: the proliferative potential defined as a labelling index (LI) of proliferative cell nuclear antigen (PCNA), the expression of intracellular domain of epidermal growth factor receptor (EGFR) and the rate of apoptosis identified by ISEL. The risk for shorter survivals increases with higher PCNA LI and with the EGFR expression in the tumor. In contrast, the rate of apoptosis is a good predictor since the risk for shorter postoperative survivals progressively reduces with high apoptotic indices. The expression of cancer proteins p53 and bc12 in the glioblastomas produces no noticeable effect on the patients survival.