Photo-ID is a cost-effective, non-invasive, capture-recapture alternative to physical tagging that uses colouration, scars and natural markings to identify animals accurately and repeatedly over space and time. This tool has proved useful when investigating the abundance, distribution, migration, behaviour and life history of wide-ranging marine megafauna in the face of anthropogenic threats and environmental change. Photo-ID can also provide valuable information on population demographics by aiding in the gender determination of individuals. Sexual dichromatism, a form of dimorphism whereby differences in colouration between the sexes exists, offers one way to discern gender. Whilst more common in birds, fishes and frogs, it has been suggested that a sexually dichromatic trait may occur in the highly patterned dwarf minke whale (DMW) (Balaenoptera acutorostrata subsp.). We applied a categorisation system to visually assess DMW colour pattern variation across 107 sexed individuals present in 2,191 images. Proportion comparison and multiple correspondence analysis revealed there were no detectable differences in colour pattern variation between the sexes. Opportunistic gender determination of DMWs by anogenital distance therefore remains the current method and a recognised limitation to data acquisition. Nevertheless, this work was an important exploratory step in the photo-ID and broader research of these little known whales.