This paper presents an account of chronic-progressive Spinobulbar Spasticity (SBS) or Primary Lateral Sclerosis (PLS), a rare syndrome involving degeneration of the upper motoneuron, on the basis of 6 clinically examined cases. Individuals of both sexes can be affected. Onset of the syndrome occurs around the age of 54, but may sometimes be before 50. Early symptoms of the disease are spasticity on one leg and disturbance of motor skills in one hand. The symptoms generalize within two to three years into tetraspasticity accentuated in the legs, accompanied by pseudo-bulbar dysarthria and dysphagia, which, however, may also be present at the onset of the disease. Compulsive laughing and crying, optokinetic disturbances and facial stiffness develop as additional, though inconstant symptoms. Disease courses of 25 years were observed. Therapy is symptomatic. Fasciculation and muscular atrophy, which would indicate a transition to Amyotrophic Lateral Sclerosis (ALS), were not observed even if the disease was of longstanding. SBS differs from spastic spinal paralysis by virtue of its greater mean age of incidence, its tetraspasticity in conjunction with pseudobulbar signs, and-so far as can be established to date-its apparent non-hereditariness. An influence of exotoxic factors has not been demonstrated so far. The clinical syndrome results from a selective degeneration of the corticospinal and cortico-bulbar tracts up to the motor cortex, where loss of original pyramidal cells has been shown to occur (Pringle et al., 1992). The paper includes a survey of the clinical and neuropathological findings in cases of SBS published so far. Extensive anamnestic and clinical records including TCMS-studies, PET and NMR-CT scans performed in the parasagittal plane are essential for early diagnosis of the syndrome.