In order to investigation the effect of planting densities and patterns on agronomic and physiological traits in basil (Ocimum basilicum L.), an experiment was done as spilt plot based on completely randomized blocks design with three replications at Qazvin region in 2013. Planting patterns as main plot in two levels included one row (30 cm) and two rows (60cm) and planting density as sub - factor in three levels (40, 60 and 80 plant in square meter) were considered. The results showed that single effect of planting densities and patterns were significant on plant height, stem diameter, number of leaf per plant and leaf area index. Also single effect of planting density was significant on leaf chlorophyll, stem fresh weight and total fresh weight in plant. The greatest amounts of studied traits obtained in 40 and 80 plant in square meter. Interaction effects were no significant about any one studied characters.