And bosses fear trade could be hit even harder unless a trade deal can be struck between Britain and Brussels before March 2019 when ties are formally severed.
IHK Managing Director Oliver Groll said the export figures mainly concerned the car industry which is major employer in the region which is home to a key Ford plant.
Saarland is often referred to as “Autoland” and nearly one in two industrial workplaces is directly or indirectly related to automotive manufacturing.
The IHK said the situation for the Saarland companies remained uncertain amid fears that export deliveries would become more expensive if trade tariffs were stamped on goods after Brexit.
Figure show some companies have already partly withdrawn from the UK market but sales and exports are also falling due to the exchange rates.
Britain has been the Saarland’s most important trading partner since 2012 and last year alone goods worth more than £2billion were shipped to the UK.
Angela Merkel’s economy minister Brigitte Zypries admitted Germany would experience trade difficulties due to Brexit but said Britain would suffer more than the remaining 27 EU members when it leaves the bloc.
Ms Zypries said: “I expect we will of course have problems with trade but it will not be so hard for Europe as for Britain.”
The minister spoke out as she delivered revised German government growth forecasts to a conference in Berlin.
Germany is taking an increasingly pessimistic view of its economy post-Brexit.
The Federation of German Industries (BDI) has warned German firms operating in the UK to brace themselves for a “very hard Brexit” and told its members to take precautions or be prepared to face heavy economic losses.
BDI managing director Joachim Lang pointed out the importance for German industry of ensuring as smooth a transition as possible, stressing that Britain remained one of nation’s most important trade partners.
German companies export £75.8bn of goods to Britain every year and German firms employ about 400,000 workers in the UK.
Mr Lang said: “The unbundling of one of Germany’s closest allies is unavoidably connected with high economic losses.
“The German economy is preparing for all possible scenarios.
“A disorderly exit by the British from the EU without any follow up controls would bring with it considerable upheaval for all participants.”