The Black Sea region of Turkey is where the Medlar population is most common, and Medlar usually grows naturally in this region. This study was carried out to determine the organic acids, sugars and bioactive compounds of promising Medlar (Mespilus germanica L.) genotypes which were grown in Tonya and Sürmene districts of Trabzon province (Black Sea Region of Turkey) in 2017 and 2018. Total of 15 genotypes were evaluated in the study, including 8 genotypes from Sürmene and 7 genotypes from Tonya. As a result, crude protein was ranged from 1.65 to 2.70%, crude oil from 0.10% to 9.40%, soluble solids contents from 9.80% to 20.20%, titratable aciditty from 0.60% to 1.40%, ascorbic acid from 21.5 mg 100 g −1 to 44.2 mg 100 g −1 , malic acid from 590.5 mg 100 g −1 to 1074.5 mg 100 g −1 , succinic acid from 127.0 mg 100 g −1 to 419.0 mg 100 g −1 , and citric acid from 2.0 mg 100 g −1 to 32.0 mg 100 g −1 , fructose from 3255 mg 100 g −1 to 4726 mg 100 g −1 , glucose from 2108 mg 100 g −1 to 3017 mg 100 g −1 , sucrose from 127 mg 100 g −1 to 399 mg 100 g −1 , carbohydrate from 47.3% to 73.1%, total phenolics from 41 mg GAE 100 g −1 to 411 mg GAE 100 g −1 and antioxidant activity 13.1 mmol TE 100 g −1 to 77.8 mmol TE 100 g −1 . It was found large diversity regarding crude oil, SSC, titratable acidity, citric acid, glucose and antioxidant capacity of fruits among the genotypes. It can be said that the fresh fruits of promising Medlar genotypes are particularly promising for the use of nutraceuticals. In particular, Ton-20 and Ton-21 genotypes were remarkable due to their high-quality characteristics and total phenolic content.