Here we present non-invasive, specific and high contrast visualization of very small EGFR overexpressing human tumours with sizes ranging from 10 to 100 mm3 in nude mice using [99mTc(CO)3]+ labelled anti-EGFR nanobody 99mTc-D10 by multi-pinhole SPECT 45 min after intravenous administration. Here, EGFR is linked to neoplasm.