News stories and patient-facing material about genetic tests are often illustrated by images, but the content of such images and the messages they propagate are rarely scrutinised. Stock image banks were searched to identify a hundred images relating to genetic tests and analysed using a multimodal critical discourse approach, aiming to identify what the images featured, how they were composed, and what they communicated about genetic testing. We found that images tended to focus on technical aspects of sample processing (for example, pipetting) and drew on older technologies (for example slab gel electrophoresis) when representing data arising from genetic tests. Composition choices like focussing images around pipette tips, or emphasising colour or brightness of electrophoretic bands, represented genetic testing as precise, unambiguous and illuminating. Only 7% of images featured a person having a genetic test, and only one image alluded to communication of genetic results. Current popular visual representations of genetic testing rarely highlight the possibility of uncertain or non-diagnostic outcomes, and may contribute to high public expectations of informativeness and certainty from such tests.