Two-minute spontaneous conversational speech of English and Cantonese was obtained from 86 Cantonese-English bilingual children. As a physical measurement of the rate of vocal fold vibration during speech production, fundamental frequency (F0) characteristics including the mean speaking F0, pitch sigma, minimum and maximum F0 values were measured from the medial 60-second portion of the speech samples by using Praat. F0 data measured from the English and Cantonese productions were statistically compared. Significant correlation was found for speaking F0, pitch sigma, and F0 range values between Cantonese and English. Results indicated that speaking F0 and F0 range values were significantly lower in Cantonese than in English. It is speculated that such difference is related to the tonal nature of Cantonese, although language proficiency may play a role in the discrepant F0 findings.