Motor neuron diseases are not frequently associated to Human Immunodeficiency Virus (HIV) infection, although some reports have mentioned this relationship, suspecting a viral involvement in the pathogenesis of this disease. A 43-years-old male with HIV diagnosis is described, who started with progressive weakness of his legs, showing further worsening 6 months later, with upper extremity and bulbar involvement. Neurophysiological studies demonstrated upper and lower motor neuron compromise in all the extremities and bulbar muscles. Other causes were ruled out. Auto-antibodies against Human Herpes Virus type 8 were positive for IgG. There were no anomalies on image studies. A change in the antiviral scheme stopped temporarily the progression of the clinical features. However, posterior withdrawal of medications due to toxic hepatitis led to worsening of signs and symptoms. This case, among the previously reported worldwide, suggests that the association between motor neuron diseases and HIV is not coincidental, this must raise suspicion in every subject with risk factors for HIV and coexistent motor neuron disease.