Perth residents have been urged to donate blood in the coming days to ensure there are enough platelet supplies, mainly for cancer patients.

The Australian Red Cross said it needed 150 donors to give blood on Wednesday, or on New Year's Eve, to generate the necessary supplies of platelets.

Blood service spokeswoman Jessica Willet said people could donate blood every three months and platelets every fortnight.

"It is particularly important over this time of year for our cancer patients because they still need blood, platelets in particular, they only last five days," she said.

She said it was always difficult to get enough blood donations during the festive season, but people did not need to stop celebrating completely.

"It's absolutely fine to donate blood after you've had a drink the night before, we just ask that you're sober when you donate blood," she said.

"So there's plenty of time for people to come in and donate blood and then you can still carry on with your New Year's eve celebrations after that."

Ms Willet said while there were able to use supplies from other states, there was a national blood shortage.

"We are able to transfer blood between states, but it is something that across the nation we are asking for more people to donate blood."

The Blood Service said there were still appointments available at the Perth donation centre.