Shrink rappers: Once, hip-hop ruled. Now its stars are reduced to petty sales squabbles and its artists are being dropped

The recent sales war between hip-hop's two most prominent artists, 50 Cent and Kanye West, proved to be the major music industry story over the last few weeks, indeed perhaps arguably over the entire summer. The two-horse race to the top of the pop charts was triggered by the pair's decision to release their new albums – 50's Curtis and Kanye's Graduation – on the same day

When 50 Cent declared that he'd permanently vacate the recording booth if he came up second best, the stakes were upped more than a few notches. But the verbal sparring over sales figures has cast light on another storm that's been quietly brewing over the last 18 months: namely, the staggering drop in overall sales of rap albums, and the apparent ailing commercial and creative health of the genre.

West may have won the battle – his final US tally of 957,000 coolly knocking 50 Cent's 691,000 into a cocked hat – but, ultimately, is hip-hop itself losing the war?

Eminem's second (and best) album The Marshall Mathers LP, which was partly masterminded by Dr Dre, shifted 1.7 million copies in its first week in 2000, and eventually more than eight million in a year. A few years later, Dre repeated the trick when he took the raw, uncut, bullet-ridden boasts of a young crime-rhymer from Queens, sanded down the rough edges and helped blast 50 Cent towards superstardom with his 7.5-million-selling debut Get Rich Or Die Tryin'.

Now, though, in the second half of the decade, rap music's clout appears to be shrinking. Sales are in decline: between 2005 and 2006 the amount of hip-hop albums shifted in the US plummeted 21 per cent. Record labels, meanwhile, are increasingly dissatisfied at the rapidly diminishing returns and are dropping artists from their rosters and slashing marketing budgets for their urban-music divisions.

Phillip Mlynar, the deputy editor of Hip-Hop Connection magazine, suggests that the current slide should be viewed as a soft landing following the boom years of 50 Cent and Eminem. "That period was not just huge in hip-hop terms but massive in pop terms, too," he says.

Even if the lower overall sales volumes currently being registered are simply a harmless return to the pre-2000 explosion days, what's fuelling this trend? Turn on any music video channel or daytime radio station, and once again it seems hip-hop is not the almighty musical and commercial juggernaut it was five years ago. Take Radio 1, for example. It recently cut the number of hours allocated to Tim Westwood's Rap Show, while the station's daytime playlist programmers appear to be increasingly shunning hip-hop for a broad sweep of new, guitar-based, bands.

One reason for this that has been proposed is that the standard of the music has declined, with rap artists failing to serve up the kind of catchy, irresistible songs – like Outkast's "Ms Jackson", Eminem's "Stan", and 50 Cent's "In Da Club".

But the problem, say other commentators, is not the quality of the music; rather it is record labels' apparent inability to effectively market anything other than standard-issue crime rap. Critical consensus holds that both Lupe Fiasco and Rhymefest – who last year both released their debut albums, Food & Liquor and Blue Collar respectively – suffered from woeful marketing, poor singles choices, lengthy release delays, and a lack of label enthusiasm after the less-than-spectacular first-week sales (Food & Liquor shifted 57,000 in the US, and Blue Collar 15,000).

"It would be great to see the major labels putting some faith in the idea of building careers, not hoping for one-hit wonders and judging them on first week sales," says Mlynar.

"Some acts seem to have been dumped before their career's been given a chance to get off the ground, largely due to reports of disappointing first-week sales. On that basis both Jay-Z and Nas's careers would have been over shortly after the release of their first album."

'Graduation' is out on Mercury; 'Curtis' is out on Polydor