The aim of this work was to investigate the influence of planting date and distance on    growth, essential oil content and composition of Rosmarinus officinalis L. plant, grown at  the Experimental Station of Medicinal and Aromatic Plants, Fac. Agric., MansouraUniv. during two successive seasons 2004 / 2005 and 2005 / 2006. The results showed significant differences in all investigated characteristics occurred between the four planting dates (February, March, October and November), three planting distances (40, 50 and 60 cm) and their interactions. The results showed that the tallest plants, highest yield of dried leaves and essential oil were obtained from February planting date compared with the other planting dates. The closer planting distance (40 cm) gave the tallest plants and heaviest dried leaves yield / fed, while increasing plant distance (50 to 60 cm) decreased plant height and yield. The wider space (60 cm) increased the number of branches, fresh and dry weights of
herb / plant, as well as produced highest essential oil percentage and content / plant compared with the closer spacing. Most of the interaction treatments exhibited significant effect on the all investigated characteristics. The early planting date (1^st February) with the narrow planting distance (40 cm) gave the best results of plant height, dried leaves yield, but the wide spacing between plants resulted in maximum number of branches, heaviest fresh and dry weights of herb per plant, yield of dried leaves and essential oil. The relative percentage of the main essential oil constituents (cineol, linalool and borneol) was greatly variable in the investigated planting spaces in relation to the planting dates. Among various metrological data, temperature and day-length were the important factors that contributed to the greatest differences in essential oil percentage through more photosynthesis. Spring cultivation (February & March) produced highest percentage for essential oil in 1^stcut, and in 2^ndcut autumn cultivation (October
and November) during both seasons. These results are very important for optimization the growing conditions for Rosmarinus officinalis L. plant under Mansoura conditions.