One hundred and sixty consecutive surgically removed colorectal carcinomas were investigated on histological sections stained with Hematoxylin and Eosin (H & E). Vascular and neural neoplastic invasion was found in 49 (30.6%) and 50 (31.3%) patients. In addition, immunohistochemical investigation was performed on step sections to those stained with H & E in the first 50 patients, using anti-human Factor VIII related antigen, anti-actin and anti-protein S 100 antisera. The percentages of positive cases for vascular invasion in this group of 50 patients were 20% on H & E sections and 62% on those stained with anti-Factor VIII and anti-actin antisera. Neural infiltration was identified in 14% of cases on H & E sections and in 70% of cases on anti-protein S 100 treated sections. Since vascular and neural infiltration are known to be ominous prognostic factors, their identification has great clinical relevance. The use of these simple immunohistochemical stains, using readily available antisera on formalin-fixed material, is recommended as routine procedure in surgical pathology laboratories.