Poorly insulated and heated homes are causing illness and costing the NHS £145m a year, according to new figures.
Respiratory conditions, strokes and hypothermia can all be caused by being too cold.
As part of a new campaign, landlords are being urged to ensure their homes are properly insulated and have working boilers to reduce the number of tenants becoming ill.
It has been launched by Friends of the Earth as part of a new campaign involving more than 35 organisations to change the law to protect tenants from cold housing.
The data for England found that 655,800 homes rented from a landlord or letting agency are so cold they are officially a health hazard, with a bottom-of-the-scale energy efficiency rating of F or G.
Friends of the Earth together with charities including Crisis, Citizens Advice and Age UK, are calling for legislation in the Government's new Energy Bill to make it an offence for landlords to re-let cold homes until they have been improved.
Friends of the Earth's warm homes campaigner, Dave Timms, said: "It's shocking that people still have to put up with cold rented homes that make them sick and cost a fortune to heat - while the NHS spends millions every year that decent insulation could help avoid."