OBJECTIVES: Human growth hormone (hGH) treatment is potentially expensive, and improvements in dosing accuracy through more precise delivery systems may lead to reductions in costs due to a minimization of wastage. To test this hypothesis, we assessed potential cost savings in the treatment of childhood growth hormone deficiency (GHD) and small for gestational age (SGA) due to differences in the precision of dosing of hGH delivery systems. METHODS: Three delivery systems with differing dose increment size were compared (Norditropin NordiFlex with dosing increments of 0.025 mg versus Genotropin Pen and Humatrope Pen both with 0.1 mg dosing increments). The recommended daily dose of hGH for each indication for 1 kg body weight intervals was combined with costs per mg hGH (taken from published UK sources) to calculate annual costs of hGH treatment for GHD and SGA patients. The calculations were based on the assumption that patients received the required daily dose as a minimum or the lowest possible injectable dose above the required daily dose. RESULTS: Due to more precise incremental dose delivery, using Norditropin NordiFlex versus the two other comparators was found to save an average of 6.2% of the annual hGH dose. This translated into annual drug cost savings of £254.32 and £179.53 per patient compared to Genotropin Pen and Humatrope Pen respectively. In patients with lower body weight, where smaller dosing increments were more critical to accurate dosing, even greater savings of up to 10% were found. These results were robust in all body weight categories and in both GHD and SGA. CONCLUSIONS: More precise dosing with the Norditropin NordiFlex delivery system compared to Genotropin Pen and Humatrope Pen led to cost savings in the UK setting in patients with GHD and SGA.