A new amyotrophic lateral sclerosis (ALS) category named 'UMN-dominant ALS' and defined as 'due predominantly to UMN signs but with minor electromyogram (EMG) denervation or LMN signs on examination' has been proposed. The clinical and laboratory features of 20 patients with UMN-dominant ALS are described here, their disease course is analysed longitudinally according to their disability progression, and all these parameters are compared with those of typical ALS patients. Ten women and 10 men diagnosed with UMN-dominant ALS were evaluated. Their mean age at disease onset was 58.6 years. At the most recent evaluation, after a mean disease duration of 7.7 years, all patients progressed to a tetrapyramidal syndrome with pseudobulbar features of varying degree. No patient had respiratory problems. Cognitive impairment was observed in eight patients. The differences in disease progression between the UMN-dominant ALS and typical ALS patients proved significant (p <0.02) both with regard to the total ALSFRS-R score at six months and to each single region subscore at 12 months. Our findings suggest that there is both a different pattern of disability and longer survival in UMN-dominant ALS compared to classic ALS patients.