The Mercedes-Benz O404 was a coach chassis produced by Mercedes-Benz between 1992 and 2001 as a replacement to the O303. It was replaced by both the OC500RF chassis and Travego integral coach products.

The O404 was available in three different lengths, named the O404-10x, the O404-13x and the O404-15x. It was also available in three different heights, the O404-xxR, the O404-xxRHD and the O404-xxSHD. Only the O404-15R was sold in the United Kingdom.

The O404 was only introduced to the UK in 1997 and sold exactly one hundred chassis, all of which were bodied by Hispano. The last O404 sold in the UK - BU51FWY to Impact of Carlisle in September 2001 - was also the last O404 sold worldwide.

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