The species is considerably larger than the eastern quoll , with males measuring up to 130 cm long and 4 kg in weight.
Females are significantly smaller than males.
The eyes and ears of the spotted-tailed quoll are comparatively smaller than those of the eastern quoll . Also the spotted-tailed quoll is physically strong in appearance, with a thick snout and wide gape. The spotted-tailed quoll is also found on the east coast of mainland Australia, but is rare. D. m. maculatus occurs from southern Queensland to Tasmania. The spotted-tailed quoll is now threatened throughout its mainland range.