You'll need to check that website, jrtv - I'm employed and no longer pay it, but I don't know how it works when you are self-employed, you presumably just no longer "buy a stamp" but you'll need some proof of exemption from HMRC to do so (I had to give the cert to my employer). The ages for exemption for women are changing (and going up on a sliding scale), not sure about males. Check that site.
Thanks everyone, I thought it was a no, had a letter from HM Revenue & Customs who wanted to know why my bank D/D had stopped and was I still woking, I have just phoned them and they say the letter was a mistake.
At least two responders failed to note that the OP said that he was self employed, not employed. Otherwise the responses are broadly correct, but fail to mention that exemption from Class 4 NIC only applies from 06 April following 65th birthday (for a male, and assuming current state pension vesting age).