They are twins and Mario is the older brother.

Mario is a few years older than Luigi!

Don't know how old they are but Mario is Luigi's older twin brother. So he's definitely older but not by much.

has anybody ever played yoshi's island.they r twins.and i think that i heard that they r 34yrs.but im not sure if that is trued

Mario was born in 1981 and Luigi was born in 1983. However, they were both born as full grown moustachio'd plumbers.

How manly! *faints*

I love it in TTYD how almost all the characters comment on his manly-ness, especially his mustache.

I always thought they were twins and Mario was born first. I could be wrong but that's what I think.

I'm pretty sure they are not twins and Mario is older by a few years.

Thats if the movie is to be believed.

The Ghost of RubangB is talking about when they first showed up in games where as nitendo says that they r twins(if u play yoshi's island then u see that they r born at the same time

I never put that much thoguht into it.