In the present study, pumpkin (Cucurbita Pepo L.) was grown under water stress to determine its effects on the chemical composition of the seeds (i.e., oil, protein, fatty acids and vitamin E), in Kayseri, Turkey. Irrigation treatments were designed to supply different portions of depleted moisture within the efficient root zone of the plants (60 cm). The treatments were arranged as supplying 100% (I-100), 80% (I-80), 60% (I-60), 40% (I-40), 20% (I-20) and 0% (I-0) of depleted moisture through a drip irrigation system. The effects of irrigation levels on the oil content of pumpkin seeds were found to be significant (p < 0.01). The oil contents of irrigation treatments varied between 26% (I-0, dry) and 64% (I-100, full irrigation). However, the effects of deficit irrigation on protein, fatty acids and vitamin E contents were not found to be significant. The vitamin E contents varied from 41.6 - 55.3 mg/100 g; while the protein contents varied from 28.5-37.7%. Six different fatty acids (linolenic, linoleic, oleic, stearic, palmitic and myristic acid) were examined. The average concentration of palmitic, stearic, oleic and linoleic acids ranged from 10.7-12.6%, 6.4-10.4%. 39.6-48.9% and 32.4-35%, respectively. Myristic and linolenic acids were not detected in the pumpkin seeds.