Why do veins look green?

Human blood is ALWAYS red. Really. Anyone who says it's blue or any other colour is mistaken.

This is plainly obvious if you ever donate blood. Phlebotomists always take blood from veins, they are required to do it without exposing it to air, and it always looks red. Likewise, any surgeon (or sausage company) will tell you that all veins and arteries are pretty much clear.

Now, I know what some of you are thinking: 'Wait a minute - I can see some of my veins and they are clearly blue!'. It's okay. There are scientists who have wondered about that too:

In a recent piece of research, it was discovered that veinous blood looks blue only because it's surrounded by much redder blood. They could even reproduce the effect by surrounding red veinous blood with a pool of red oxygenated blood. the veinous blood looked blue when submerged!

And so it goes with other colours as well. Many people have pigments in their skin that can alter the apparent colour of veins and arteries underneath. But this hardly means that they actually ARE different colours, of course!

There are creatures in the world that do not have red blood - some have greenish-blue blood because they use copper atoms to attract oxygen instead of iron. It doesn't work anywhere near as well, unfortunately for octopi and mollusks out there.
you must be a vulcan
Are you an extraterrestrial?
You have blue blood in some of your veins . it might look a little greenish when viewed through your skin. (Of course as soon as the blue blood hits air (meets oxygen) it turns red, so that's why no matter where you cut yourself, you see red only not blue.)
because our blood is blue until oxygen is involved, then it's red
they dont look green
blood is blue. if your veins are green then you might not be human. do you have scales and a tail? a long forked tongue and red beattie eyes?
Because in veins the oxygen leaves the blood goign to other places in your body, which leaves the carbon dioxide. And the blood turns dark blue which looks green through ur skin.
too much cabbage
mine are blue.

diabolik if your bloods blue then you need to see a doctor asap.
The blood in arteries looks bright red because it is oxygenated. As the blood goes through body, it drops off the oxygen and picks up carbon dioxide and other waist materials. This changes the color of blood from bright red to dark red. That is why it looks like veins are greenish blue.
mine do not
I thought they looked blue
Green? And what colour is the sky on your planet?
Cause you are colour blind?
Mine look blueish:).
It's the pigment in your blood.
The condition of your blood.
How much liquid you have been drinking, water ,juices all contribute to the color of your blood.
Your race (darker skin doesn't show the veins as blueish or In your case green:).
This is from;http://sln.fi.edu/biosci/vessels/veins.h.
this sit ehas some good information.

Because it lacks oxygen, the waste-rich blood that flows through the veins has a deep red color, almost like maroon. Because the walls of the veins are rather thin, the waste-rich blood is visible through the skin on some parts of the body. Look at your wrist, or hands, or ankles. You can probably see your veins carrying your blood back to your heart. Your skin refracts light, though, so that deep red color actually appears a little blue from outside the skin.
I may be completely wrong here. but the veins that carry blood BACK to the heart are green because the blood in them lack oxygen. It is only after is has gone through the lungs and therefore replenished of oxygen that the veins that carry it are not greyish green. More or less the same reason why we go blue when we are being strangled ! Now let's have a doctor or nurse give us the REAL reason.
Mine don't
chloroplast. they contain chlorphyll that is green, used for photosynthesis.
hhhhhheeeeeeeeeeellllllllppppp. ur an alien!! call 911! Call the president!! call the MEN IN BLACK!!!!!!!!!!!!!.
Yes good question, I've read all about you reptiles disguised as humans waiting to take over the world, I think your disguise may need touching up a bit?
Go and see your chief croc asap!
Veins aren't green, they're either blue or red. The blue veins are unoxynated blood and the red known as arteries are oxynated blood.
they look blue because the haemaglobin in the blood in the veins is deoxygenated. oxygenated haemoglobin is red, deoxygenated haemoglobin is blue. there is oxygenated blood in your arteries, deeper under your skin, and deoxygenated blood in your veins, which run closer to the skin surface.
it carries deoxygenated blood..
It'll probably be because you have a yellowish skin tone(Naturally, I mean, I'm not talking about jaundice!) and veins are blue.

Blue and yellow make green, ergo your veins appear green. Mine look blue.
oh dear. others have said what i was going to say!