In this study, the activity concentration of 226Ra, 232Th, 40K, and 137Cs in some vegetable and fruit samples frequently consumed in Kastamonu province located in the West Black Sea region of Turkey were determined using a gamma-ray spectrometer. The activity concentrations of 226Ra, 232Th and 40K varied from 0.8 ± 0.1 to 32.8 ± 1.3, 0.7 ± 0.1 to 41.3 ± 21 and 391.8 ± 18.3 to 4679.0 ± 311.4 Bq kg−1 (dw), respectively, in twenty-eight vegetables and 1.3 ± 0.1 to 12.6 ± 0.4, 1.4 ± 0.1 to 15.0 ± 0.5 and 133.0 ± 84 to 777.0 ± 69.4 Bq kg−1 (dw), respectively, in seven fruit samples. The highest activity concentration of 226Ra and 232Th was measured in the garlic sample, while the highest activity concentration of 40K was measured in the spinach sample. Artificial radionuclide 137Cs was measured only in four vegetable samples; its activity concentration in garlic, eggplant, cucumber and carrot samples was determined as 9.6 ± 0.3, 3.1 ± 0.1, 3.1 ± 0.1 and 2.2 ± 0.1 Bq kg−1 (dw), respectively. The results obtained were compared with the results of similar studies in the literature. Annual effective radiation dose to adults due to the internal irradiation caused by ingestion of the investigated vegetable and fruit samples, and the corresponding excess lifetime cancer risk were estimated as 201 µSv and 8.9 × 10−5, respectively. The contribution of 40K to the total annual effective radiation dose was found as approximately 70%.