Recent reports indicate that patients with malignant melanoma might be at higher risk for developing a non-cutaneous unrelated second malignancy. We describe the case of a 46-year-old woman who had a malignant melanoma on her right shoulder that was treated in 1998 by surgical excision combined with axillary lymph node dissection. In 1999, ultrasound examination of peripheral lymph nodes revealed one suspicious echopoor structure in the woman's right axilla that was not palpable. Diagnostic excision and histopathological examination revealed a small B-cell lymphocytic lymphoma, and further investigations led to a diagnosis of chronic lymphocytic B-cell leukaemia (B-CLL). We would like to point out the value of high-resolution ultrasound examination in the follow-up of patients with malignant melanoma; this examination can detect early metastasis as well as other unrelated malignancies.