Pesticide Action Network Europe, an umbrella organisation for concerned groups in Austria, France and Germany, said it had "uncovered substantial evidence" of contamination by studying 40 sample bottles of wines.
The wines were of Australian, Austrian, Chilean, French, Italian, German, Portuguese and South African and included six wines produced through organic farming.
The non-organic bottles of wine contained on average traces of four pesticides; one revealed 10 different pesticides.
The group's analysis found 24 specific pesticide contaminants, including five it said were classified by the European Union as being carcinogenic, mutagenic, reprotoxic or endocrine disrupting.
Of the six organic wines tested, only one contained traces of pesticides, at low levels and probably because of such chemicals in neighbouring plots.
"Many grape farmers are abandoning traditional methods of pest control in favour of using hazardous synthetic pesticides," Elliott Cannell of PAN Europe said. "This trend has a direct impact on the quality of European wines."
German Green Euro MP Hiltrud Breyer called results "alarming" and urged EU member states to ban dangerous pesticides.
"Now the EU is reviewing the authorisation of pesticides, it must seize the opportunity to ban those that are dangerous," she said.