Peaches (Prunus persica L., Batsch; cv. Glohaven) and nectarines (P. persica L., Batsch, var. nucipersica; cv. Maria Laura) were picked weekly from 57 days after full bloom (DAFB) to complete ripening on the tree in order to study the changes in volatile composition during fruit growth and ripening. Volatile substances were sampled from sliced pulp by dynamic headspace and analyzed by capillary Gas Chromatography (cGC) and gas chromatography/mass spectrometry. Volatile composition varied greatly, both quantitatively and qualitatively over time and between cultivars. Aldehydes, alcohols and esters showed a decreasing trend during fruit growth, with the exception of acetoin and (Z)-3-hexenol which reached the highest amounts in mature fruits. Glohaven peaches produced great amounts of lactones, mainly gamma- and delta-decalactone, and gamma- and delta-dodecalactone. Maria Laura nectarines produced less Volatiles but more of esters and terpenoids (linalool and terpinolene) than peaches. As a consequence, nectarine aroma was more floral and fruity. (C) 1997 Elsevier Science B.V.