Background: Intrathecal injection of sufentanil offers labour pain relief of short duration. This double-blind randomised study evaluates if the combination of adenosine to sufentanil could give relevant prolongation (40%) of the duration of sufentanil spinal analgesia. Methods: Twenty-five healthy parturients requesting labour analgesia were included. Patients received 10 µg of sufentanil + 500 µg of adenosine or 10 µg of sufentanil intrathecally. Pain intensity and duration of pain relief were assessed. Results: Pain relief was equal between groups. Duration of analgesia was not increased by adenosine + sufentanil, 99 ± 54 min, vs. sufentanil, 89 ± 56 min. Conclusion: Adding 500 µg of adenosine to 10 µg of sufentanil could not provide any prolongation of labour pain relief.