Bob Brown has resigned as Leader of the Australian Greens Parliamentary Party. He will also resign from the Senate, after 16 years' service, when his Tasmanian replacement is available in June.

Senator Brown, who is 67, made the announcement to his Greens Party Room colleagues this morning at 10am.

"I am sad to leave but happy to go. It is good knowing that the Greens have such a depth of talent and experience lined up for leadership - I could only dream about that a decade ago", Senator Brown said.

"It is prime time to hand over the reins. I offer a huge 'thank you' to the 1.7 million Australian voters who elected our Green team, and to my 9 colleagues: they have made each Green year in this parliament better than the year before - though the best is yet to come. For example, our policies for fairly taxing the resources boom and  carbon polluters, uniquely enable the Greens to fund a national disabilities insurance scheme, the Gonski education reforms, Denticare, renewable energy businesses, as well as progress on High Speed Rail linking our major cities.

"I also thank my splendid staff, including my longtime friend, confidant, and fount of good political sense, Chief of Staff, Ben Oquist," Senator Brown said.

Senator Brown has called the Governor-General, the Prime Minister and the Leader of the Tasmanian Greens to inform them of his resignation.

"I look forward to fresh green pursuits including writing, photography, music, occasional talks, bushwalking, and getting out with Paul to see Miranda Gibson who has been perched for 120 days 60 metres high, in defence of a giant tree facing destruction in central Tasmania," Senator Brown said.