A-level physics is "under siege" as teenagers drop the subject and both physics and chemistry face shortages of specialist teachers, they said.
The Royal Society, the Institute of Physics, the Royal Society of Chemistry, and the Association for Science Education have set up a new organisation, Score, to campaign for improvements in science education.
Professor Martin Taylor, vice-president of the Royal Society, said: "We have a window of opportunity in the next five years to ensure we stem the decline in the sciences. If we get this wrong, we risk losing a generation of scientists.
"We need young people to be inspired by the sciences and mathematics, so that they choose these subjects in sufficient numbers to ensure that the UK's economy prospers and that we retain our place as a world leader in science and technology.
"Science education is facing troubled times. In particular, A-level physics is under siege.
"This year A-level entries in physics reached a new low, with a massive 37 per cent fewer students choosing to take the subject than in 1991.
"And the Government also faces huge challenges concerning getting more specialist science teachers into schools."
Derek Bell, the chief executive of the Association for Science Education, said: "Ensuring high-quality science education is available to all young people requires a clarity of purpose and strong support for both our teachers and pupils."
Peter Main, director of education and science at the Institute of Physics, said the campaign would create a more coherent voice for the science education community.
He said: "Our aim is to build upon the recent upturn in the number of young people continuing to study mathematics after GCSE level and extend that trend to science."
A Department for Education and Skills spokesman said: "Increasing the number of scientists is a priority for this Government.
"A renewed focus on the sciences - particularly physics - through our pound;30 million science strategy will deliver 3,000 more specialist teachers (and) changes to the GCSE, and the introduction of single science awards will attract and engage more young people with the sciences."