The present study was conducted during the two successive seasons of 2002/2003 and 2003/2004 at the Farm of Ornamental Horticulture Department, Faculty of Agriculture, Cairo University to investigate the effect of irrigation intervals every 7, 11or 15 days and bio- fertilizers ( Nitrobien and Phosphorein) each at 0, 3 or 6 g / pot on chamomile plant. The results showed that prolonging irrigation interval to 11 or 15 days significantly decreased both fresh and dry weights of flowers in both seasons. The highest fresh and dry weights  of flowers were obtained due to irrigation every 7 days . Irrigation every 7 or 11 significantly increased oil percentage  in the first and second seasons ,respectively. Irrigation every 7 days gave the highest α pinene, sabinene, ρ-cymene, 1,8-cineole,  bisabolon oxide A, chamazulene  and dicycloether . Whereas irrigation every 11 days gave the highest percentage of bisabolol oxide A. Irrigation every 11days gave the highest N contents , while irrigation every 15 days gave the highest P and K contents. Irrigation every 7 days gave the highest total carbohydrates content.    
In general, Nitrobien and Phosphorein application at 3 or 6 g /pot significantly increased fresh and dry weights of flowers. Nitrobien at 3 or  6 g / pot in both seasons and Phosphorein at 3 or 6 g /pot in the second season  significantly decreased oil percentages. Nitrobien at 3 or 6 g /pot gave the highest bisabolol oxide A contents in chamomile oil. Whereas Phosphorein at 3 g /pot resulted in the highest ρ- cymene, 1,8- cineole and caryophyllene percentages. Phosphorein at the highest rate (6 g /plant) gave the highest  α- pinene, sabinene and chamazulene contents. Bio- fertilizers ( Nitrobien or Phosphorein ) each at    3 or 6 g / pot increased both N, P , K and  total carbohydrates contents in most cases compared with the control. Both Nitrobien and Phosphorein at 6 g /pot plus irrigation every 7 days gave the highest fresh and dry weights of flowers. Irrigation every 11 days and Phosphorein at 6 g /pot gave the highest oil %  in the first season and P % in the second one. Nitrobien  at 6 g /pot plus irrigation every 15 days gave the highest N%. Whereas Phosphorein at 3 or 6 g /pot and irrigation every 7 days gave the highest K and carbohydrates contents.