Paul Biya says he wants another 10 years in office
The opposition in Cameroon is staging a "day of mourning" to protest against changes to the constitution.
The constitutional amendment will allow President Paul Biya, 75, to seek re-election in three years' time.
The opposition Social Democratic Front (SDF) is asking people to wear black and stay at home.
The BBC's Randy Joe Sa'ah in Yaounde says not many people seem to have stayed away and business appears to be going on as normal.
It is thought people are more concerned with the cost of living than engaging in political action.
But he says that a few people are wearing dark clothes.
Similar reports have come from the other main cities of Douala and Bamende.
Soldiers are patrolling the streets of Yaounde and there is an atmosphere of intimidation, our correspondent says.
Cameroon's Minister of Special Duties, Paul Atanga Nji, predicted people would not heed the stay away saying: "Cameroonians are confident their future lies in the hands of the government".
But SDF Secretary General Elizabeth Tamajong said the action would have an impact.
"It is a pacific way of doing things and that hurts. The president will notice what is going on," she said.
Paul Biya has been president of Cameroon for 26 years.
He has said he wants to remain head of state for another 10 years.
On Thursday, members of parliament voted to scrap presidential term limits, enabling him to run for the presidency again in 2011 and stay in power until 2018.
Dozens of people were killed in February during protests against the change, which was signed into law last week, as well as rising food prices.
Correspondents say once before parliament, the bill to remove presidential term limits was always likely to be approved as the governing party has an overwhelming majority in parliament.
There were violent protests in February
The SDF has just 15 of the 180 seats and decided to boycott the debate.
When asked the reasons for the boycott, the leader of the SDF in parliament, Joseph Banadzem, told the BBC: "The whole issue is a complete fraud. We do not want to legitimise it by taking part."
BBC West Africa correspondent Will Ross says the effort to extend President Biya's time in office is widely unpopular among Cameroonians, many of whom feel the politicians are not doing enough to tackle the widespread poverty.
In his end of year state address, Mr Biya said having presidential term limits was unconstitutional and added that there were popular calls for him to stay in power.
President Biya came to power in 1982 and revised the constitution 12 years ago, extending the presidential term of office from five to seven years.