This study was conducted at the experimental area of the Department of Field Crops, Faculty of Agriculture, Cukurova University as a main crop in 2013 and 2014. The objective of this study was to determinate the effect of harvesting dates on yield and some agronomic traits, seed and oil quality of peanut (Arachis hypogea L.) grown in the Mediterranean region. The experimental design was a Randomized Complete Block Design with three replications. The Halisbey peanut variety (Virginia market type) was used as a plant material in this research. Pod yield per hectare, shelling percentage, 100-seed weight, protein and oil percentage, fatty acids (palmitic, stearic, oleic and linoleic acids) composition and oil quality (oleic acid to linoleic acid ratio, iodine value) traits were investigated. According to a two-year average, the highest pod weight (84.24 g plant(-1)) and pod number (36.83 no. plant(-1)) per plant was obtained when the plants were harvested at 180 days after planting (DAP). The shelling percentage and 100-seed weight increased when the harvesting was delayed. The highest pod (8002.6 kg ha(-1)) was obtained when the plants were harvested at 180 DAP. The oil and protein percentage ranged from 48.66-49.66% and 24.65-25.89% respectively. The oleic and linoleic acid content varied between 51.54-54.94% and 24.65-26.78%, respectively. Oleic acid to linoleic acid ratio (O/L) increased when the harvesting time was delayed.