Political leaders received plenty of exposure, with an effigy of US President George Bush figuring on one float, backside bared, in the city of Mainz while German opposition leader Angela Merkel ran up a ladder behind.
Despite some outcry, organisers there said they were not caving in to any censorship, despite the planned visit to Germany by Bush on 23 February.
In Cologne, where the biggest parade got under way at 11 minutes to 11am, one float was arranged to get mileage from the recent scandal to hit German football involving alleged bribe payments to a referee.
Around 10,000 people, many costumed as jesters or fools, and more than 120 marching bands were expected to take part in Cologne, distributing sweets in sunny but chilly weather.
Organisers said they were not
caving in to censorship
The five days of carnival involve major parades and festivities in cities such as Cologne, Mainz, Duesseldorf and Bonn before Shrove Tuesday (Mardi Gras), and up to two million people were expected to turn out until Monday.
During the carnival, revellers fill the streets to parade, catch sweets thrown from floats and listen to live music. Beer consumption soars.
The crowds sing, dance and shout themselves hoarse.
The carnival also has a following outside the Rhineland. On Sunday, an estimated 750,000 people turned out for festivities in the capital Berlin.