Apomorphine hydrochloride is used to treat refractory motor fluctuations in advanced Parkinson's disease. Delivery by infusion is associated with the formation of hard subcutaneous nodules, which may be painful, limit available infusion sites, and interfere with absorption of the drug. Diagnostic ultrasound was used to image affected tissue in 12 people experiencing apomorphine nodule formations. It revealed significant departures from normality in dermal and subcutaneous tissue, including a variety of nodule appearances, dermal thickening and diffuse changes consistent with inflammatory reactions. Sonographic appearances differed markedly between individuals, but no clear correlation between severity of tissue changes, patient demographics and apomorphine dose was observed. Diagnostic ultrasound may be useful as a non-invasive method of assessing subcutaneous nodule formation, to measure changes in affected tissue over time and after treatment.