The changes in basal area, volume and tree shape in an ‘optimum fertility trial’ in Norway Spruce were studied after the treatments had been applied for 15 years. There was a marked response to N and a lesser response to P. Increased average tree taper was associated with the N application. Form factors tended to show less change, but, even allowing for tree height responses, there was up to a 10% reduction. Phosphate fertilizer in the presence of N increased form factor slightly; applying a ‘complete’ fertilizer reduced form factor and increased taper while the trees were under about 6 m tall. The use of individual treatment regressions of volume on basal area resulted in increased precision in estimating the volume of individual treatment means.