The use of ultrasonics as an analytical technique to estimate the composition of a fermented meat-based product (sobrassada) was assessed. Moisture, fat and protein contents and ultrasonic velocity at 4, 8, 12 and 25 degreesC were measured in samples using different formulae. In this study, it was considered that a meat-based product is formed of three different constituents: fat, water and protein + others. Ultrasonic velocity was related, by a semiempirical equation, to the composition and the ultrasonic velocity of the above three components. The ultrasonic velocity temperature dependence allowed the determination of fat, moisture and protein + others contents. The explained variance was 98.0% for protein + others, 97.6% for fat and 95.6% for moisture. The results obtained show the feasibility of using ultrasonic velocity measurement to assess, in a rapid and non-destructively way, the composition of a meat-based product. (C) 2003 Elsevier Science Ltd. All rights reserved.