To quantify several acoustic features of the voice in patients with Parkinson's disease (PD) not treated with dopaminergic drugs, 22 PD patients and 28 age and sex-matched controls were studied. The Computerized Speech Lab 4300 program (Kay Elemetrics) was used. Two seconds of a sustained /a/ and a sentence were captured with a microphone and laryngograph equipment. Measures included fundamental frequency (F(0)), frequency perturbation (jitter), intensity perturbation (shimmer), and harmonic/noise ratio (HIN) of the vowel /a/, and frequency and intensity variability of a sentence, phonational range, dynamic range at the natural frequency, maximum phonational time and s z ratio. All subjects underwent indirect laryngoscopy and/or laryngeal fibroscopy. When compared to controls, PD patients showed higher jitter and shimmer, lower H N ratio, and lower frequency variability of the sentence in the microphonic signal and reported a higher frequency of presence of low voice intensity, monopitch, harshness, voice arrests, and tremor.