The majority of science laboratories in schools across Britain are not up to scratch, a survey suggests.
The Royal Society of Chemistry found 65% failed to get a "good" or "excellent" rating.
The society is concerned that cut backs in practical lessons is undermining efforts to get pupils more interested in science.
The society's president-elect, Dr Simon Campbell, said chemistry was especially hard hit by a loss of practicals.
Earlier this year, a survey by Save British Science found practical science lessons in more than three-quarters of 67 secondary school in England had been cancelled.
In 57% of those cases the reason given was the rowdy behaviour of pupils.
Bad behaviour was seen as a bigger problem than lack of equipment, large class sizes, and shortage of laboratory space.
"Fewer kids are having practical classes, largely because of poor discipline. Teachers are worried about pupils misbehaving," Dr Campbell said.
"If there is a lack of discipline in the lab, it makes teachers feel very vulnerable. They're going to get the blame if something happens, and they're afraid of litigation.
"You don't have the same safety issues with a classroom-based subject, like French for example."
Concern for chemistry
Chemistry was hit especially hard by the loss of practical lessons, he said, and school leavers who were not taught how to conduct real chemistry experiments were denied skills needed by universities and employers.
"You can't become a pilot by only training in a simulator," said Dr Campbell.
Too many pupils are not getting a chance to carry out experiments, says survey
"I think it's very serious, because chemistry is one of the key fundamental disciplines. Pharmacy is very dependent on chemistry, as is any study of new materials."
The director of Save British Science, Dr Peter Cotgreave, also expressed concern about the decline in practical lessons.
"To my mind doing away with practicals is deeply damaging. Not everyone's going to want to be a chemist, but even if you don't pursue a career in science, in a modern democracy we have to make decisions about things like GMOs (genetically modified organisms), BSE or nuclear power.
"How can you do that if you don't understand what an experiment is, and what a control group is, and how it all works?"