Introduction - Seedlessness is an important characteristic demanded by consumers of citrus fruit and gamma irradiation is a common technique used to obtain seedless citrus fruits. The present study was conducted to investigate the fruit quality and nutritional bio-components of seedless lemons (Alatac 'Uzun' and 'Gulsen') recently developed by using gamma irradiation in comparison with the original seedy cultivar. Materials and methods - High-performance liquid chromatographic methods together with UV and refractive index detectors were employed to identify and quantify these compounds. Results and discussion - Fruit quality and bio-chemical properties were affected differently; some cultivars presented no changes compared to the control, while others exhibited significant differences. The seedless lemon fruits under study were characterized by high ascorbic acid contents (262.48 to 410.74 mg LA), high total soluble solids, and high fructose and glucose contents. Conclusion - Budwood irradiation is considered as a suitable technique to improve citrus cultivars, produce seedless cultivars and raise the content of health-promoting compounds. The present results revealed that irradiation technique affected the bioactive properties of lemon.