Romulans tend to look somewhat like Vulcans, but with a slightly different forehead structure. Typical physical makeup and attributes for the common Romulan male and female are listed below. Romulan males have facial features that are generally softer then the sharp angular features of their Vulcan cousins and have a strength two to three times stronger than that of the average non-Romulan humanoids they have so far encountered. Romulan females, like the males, generally are of greater strength then those of other humanoid races. Their facial features are softer than the chiseled features of the males, with Romulan ears being slightly less pointed than their distant cousins the Vulcans.

Romulan blood chemistry is significantly different from that of Terrans. Like their Vulcan ancestors, the Romulan's have copper-based blood, which is green rather than red. The Romulan physiology is not identical to that of Vulcans however, since the two races have had two millennia to evolve and develop in different directions. Living on the two homeworlds, which are somewhat colder and a good deal wetter than Vulcan, the Romulans have undergone a few changes. Their long pointed ears, used by Vulcans to radiate excess heat, have shortened somewhat. Romulans have slightly more exterior insulating body fat, and lack the gaunt look of Vulcans. Romulan skin is a slightly lighter shade of green than Vulcans, since they do not need the extra protection from a sun provided by excess skin pigmentation.

Unlike other races whose eye and hair color may vary drastically, that of the Romulans does not. Romulans have either dark brown or black hair, which is also true of their eye color, again, either dark brown or black. Due to its xenophobic nature, the Romulan society does not tolerate anything less then pure Romulan, so diversion from the above is generally considered somewhat of a social stigma. They would in no way associate theirselves with a lesser race by unnaturally coloring their hair or eyes and are already physically ideal for their environment, therefore there is no reason to alter the natural state of things. For example, you will never see a blond-haired, blue-eyed Romulan or something other than listed above

As the Romulans are descendants of the Vulcans, subjected to millenia of evolution, they share the long Vulcan lifespan, albeit to a slightly lesser degree. The maximum Romulan lifespan that can ever be expected is approximately 250 standard years, with more typical figures ranging from 200 to 230 or so. Generally, the last 10 to 25 of those years is spent in a weakened state, as is common with most races. As is to be expected by their longer lifespan, Romulan physical development proceeds at a slower pace than their human counterparts, lagging behind humans by approximately five to ten standard years early on in life. Knowing this, the primary developmental difference between Romulans and Humans occurs later on in life, where the more hardy and developed Rihannsu physiology allows for a lengthened adult life.

Appropriately, the Romulan gestation period is slightly lengthened, with the typical child being born after approximately twelve months of development. Birth weight is generally in the same proportion to the human counterpart as are adult weights.

Finally, birth rates generally run slightly higher than their human counterpart, with an average of four children born to a Romulan family. This can primarily be attributed to the fact that early life on the homeworlds was so harsh, requiring a higher birth rate if the species was to survive. As the milennia progressed and conditions on the homeworld became more bearable and the population stabilized and grew, this average birth rate slowly decreased to the level it is today. Further, child bearing generally does not occur until both male and female are fully in adulthood. It is not considered socially acceptable in Romulan society to bear children in one's teens, although it is physically possible.