Concordance with growth hormone (GH) therapy in 75 children was objectively assessed using data on GP prescriptions over 12 months. 23% missed >2 injections/week. Lower concordance was associated with longer duration on GH therapy (p<0.005), lack of choice of delivery device (p<0.005) and short prescription durations (p<0.005), and predicted lower height velocities (p<0.05).