Blood was drawn after the intranasal administration of 325 μg DDAVP from altogether 420 blood donors at 5 blood banks in Sweden. No significant side‐effects were observed. The DDAVP plasma was pooled in two separate batches. Matched pools of control plasma from the same donors were also prepared. From each pool a separate batch of high purity factor VIII concentrate (Octonativ) was produced.The yield of VIII:c in the DDAVP batches was 2.6 and 1.5 times higher than in the corresponding control batches. The specific activity was 2.8 for the two DDAVP batches and 2.0 IU/mg protein for the control batches. Thein vivorecovery was about 100 per cent for all the batches when examined in 5 patients with severe haemophilia a. The individual half‐lives (late phase 5–48 hours) varied between 7 and 17 hours. No significant differences between the batches derived from the DDAVP and the control plasma could be detected.Thus, intranasal DDAVP seems to be a safe and practicable means of improving the production of factor vIII concen