BACKGROUND The natural history of incidentally discovered testicular microlithiasis in children has not been well defined. Although a benign condition, this entity has been found to be associated with testicular malignancies. OBJECTIVE To determine the spectrum of sonographic findings and clinical implications in children with testicular microlithiasis. METHODS During a 3.5-year period, 850 scrotal examinations with grey-scale US detected testicular microlithiasis in 16 boys (1.9%), age range 6-18 years. The US records of these patients were retrospectively analysed for distribution and pattern of this finding. The presence of intratesticular pathology was determined and the medical records and pathological reports were reviewed. In five patients, US re-evaluation up to 6 years could be performed. RESULTS Typical punctate hyperechoic foci were found bilaterally in all cases except five, which showed only unilateral foci. Additional pathology was depicted in four patients (chorioncarcinoma n=1; a cystic lesion in a patient with a large-cell calcifying Sertoli-cell tumour, n=1; diffuse structural alterations after orchidopexy, n=2). No testicular tumour developed during clinical follow-up. CONCLUSIONS The association with benign and malignant testicular tumours, as described in adults, also seems valid in the paediatric age group. Therefore, children with testicular microlithiasis should have clinical and US long-term follow-up.