With back-to-school shopping in full swing you would think a new pair of jeans is at the top of most school kids' lists, but you would be wrong.
A growing trend in casual wear is all about comfort, and denim is still struggling to find its place. Retail and fashion experts alike are not afraid to admit the look, now coined "athleisure," is all the rage from teens turning to leggings instead of jeans and moms sporting their yoga-wear everywhere and all day long.
"There isn't an 'it' item for back-to-school like we had two years ago," said Dana Telsey, CEO and chief research officer at Telsey Advisory Group. "What there are, there are certainly dusters and dresses, there's these crop tops that seem to be working and anything with the athletic bent. Athletic and activewear are certainly the new everyday wear and that's happening no matter what age people are."
So is denim suffering a slow death or is it just a victim of fickle fashion trends? Only time will tell. Jean sales are down 6 percent year-over-year, according to NPD Group and retailers have taken notice.
"A 6 percent drop may not seem like much, but it's rare for denim to take such a dramatic drop. It's a commodity business, we buy it and replenish it all the time," said Marshal Cohen, chief industry analyst of The NPD Group.
VF Corp, which has brands like Lee, Wrangler, Seven for all Mankind and Rock & Republic under its umbrella, noted the decline during its second-quarter earnings conference call in July.
"In the Americas, the jeanswear business was down to a low-single digit rate due to continued challenges in the U.S. mid-tier channel and the ongoing unfavorable women's denim trend," said Scott H. Baxter, VF Corp's group president of Jeanswear Americas, Imagewear & South America and vice president.
Read More13 retail tactics: Are they working?
Though the pace of the decline was in line with VF Corp's expectations here in the U.S., it comes in stark contrast to the European market where the company said its jeanswear had an "exceptional" quarter.
To combat the denim doldrums VF Corp said it will soon open a "global denim innovation center," but declined to give further details.
However, Piper Jaffray's picks for benefiting from the downtrend in denim include VF Corp because the company also has a healthy portfolio of athletic wear brands such as The North Face, Timberland and others.
From the beginning of the year through June, VF Corp's total jeanswear revenue are down 3 percent, though sportswear revenue is up 4 percent and its outdoor and action sports revenues grew 15 percent over the same time period.
VF Corp isn't the only retailer feeling the hurt. Piper Jaffray's biannual "Taking Stock of Teens" survey shows over the last two years teen girls' brand preferences have moved away from denim-centric names like Levi's, Guess, American Eagle, Miss Me Jeans and True Religion and more toward athletic names like Nike, Lululemon, Gap's Athleta brand, UnderArmour, Black Diamond, Urban Outfitters and L Brand's Victoria's Secret.
Read MoreMany retailers offer costly credit
Upper income female teens surveyed by Piper Jaffray listed leggings/Lululemon as the top fashion trend for two seasons in a row. Part of the blame for the denim doldrums, according to Piper Jaffray's study, is the lack of "fashion newness" in the market and the innovation of fabric technology in recent years for performance bottoms.
That innovation is now driving jeanswear companies to diversify in order to stay current with the consumer.
Joe's Jeans is turning to "alternative fabrication" and will be introducing several non-denim programs for the fall to include leggings made with "innovative textiles." The company reported on its second-quarter earnings call in July it recognizes leggings is one of the fastest-growing segments in the market.
The Gap, which may be bucking the trend through its sportswear retailer Athleta, reported a better-than-expected 2 percent rise in same-store sales for July, and increased its second-quarter earnings forecast. The retailer told CNBC the denim fatigue fad is not new.
"Fashion denim is cyclical. Currently, mid- and high-waist denim styles are trending, in addition to soft pants. Denim is still a dominant category for us at Gap and Old Navy, and we are committed to continuous innovation," said Edie Kissko, a Gap spokeswoman.
But Cohen begs to differ, saying the risk for retailers is that the "athleisure" love affair could have a lasting effect.
"It caught the denim makers by surprise because they have never really seen it before," said Cohen, "Trends today don't come and go, they come and linger. So if the consumer has migrated away from denim, it's going to be very hard to win them back."
—By CNBC's Sabrina Korber and Courtney Reagan