Monovarietal grape marc distillates, produced by traditional distillation of marcs from the most important grape varieties in Istria, were characterized on the basis of volatile aroma compound composition. In produced distillates, as well as in different fractions of the distillates, the most important primary and secondary aroma compounds (terpenes, C13-norisoprenoids, methanol, higher alcohols, fatty acids, esters, aldehydes, ketones and acetals) were identified by gas chromatography-mass spectrometry (GC/MS), while their amounts were determined by gas chromatography with flame-ionization detector (GC/FID). The differences in volatile aroma compound composition between distillates made from different grape varieties were determined using statistical methods. The distillates were subjected to sensory evaluation by the DLG method, and correlations were determined between the amounts of aroma compounds and sensory quality. It was concluded that basic aroma of all investigated monovarietal grape marc distillates consists of the major secondary aroma compounds such as higher alcohols, volatile fatty acids, volatile esters and acetaldehyde, and in some cases, 1-hexanol. Distillates made from red grape varieties Teran and Cabernet Sauvignon contained higher amounts of the majority of secondary aroma compounds, but it was assumed that their amounts mostly depend on the quality of grapes and production parameters. Marc distillates made from Muscat blanc and Muscat rose of Porec grape varieties were characterized by pronounced primary muscat aroma, due to high amounts of monoterpenes. Malvazija istarska grape marc distillates were characterized by very high methanol content. It was determined that increased amounts of middle-chain fatty acids, and especially their ethyl esters, as well as other esters, could be used as indicators of higher sensory quality, while increased amounts of sesquiterpenes, diterpenes, C6-alcohols, methanol, acetic acid, short and long-chain fatty acids and their ethyl esters, acetates and aldehydes could be utilized as indicators of lower sensory quality of grape marc distillates.