The term "frontal lobe syndrome" comprises a variety of different clinical syndromes produced by focal lesions involving the prefrontal cortex. However, similar syndromes can be observed after lesions involving subcortical structures connected with the prefrontal cortex in neuronal networks. With respect to the different clinical pictures and underlying brain lesions, prefrontal lobe dysfunction may be divided into a disorganized type, caused by lesion of the dorsolateral prefrontal lobe and its connections, a disinhibited type that can be observed following lesions of the orbitofrontal cortex, and an apathetic type following lesions affecting the functional balance between the cingulum and the supplementary motor area. As intracerebral lesions are rarely limited to the brain regions described, in the majority of patients various degrees of behavioural dysfunction can be observed. The case reports of four patients illustrating the three major prefrontal syndromes following severe head injury (n = 2) or cerebrovascular disease (n = 2) are presented and diagnostic implications as well as possible treatment strategies are discussed.