Using plasma chemistry, carbon was extracted from charcoal paint samples collected from megalithic monuments in north-west Iberia. Nine accelerator mass spectrometric radiocarbon dates on these paints establish their age to be within 1000 14C years of each other, centred at approximately 5000 BP. These radiocarbon ages for megalithic paintings fall within the proposed time period for north-west Iberian megalithic culture. Multiple layers of paint on some stones show that more than one painting episode occurred.