One of the major causes of Asian elephant population declining is the reduction of mating and giving a birth, which has to be solved by captive breeding management program in order to increase the number of elephant. One method is the estrous determination which can help the breeding management to find the optimal time for natural or artificial breeding, which is only 3-4 days in the total estrous cycle of 16 weeks. Numbers of female Asian elephants are investigated for estrous cycle and optimal breeding period by the following methods; 1) serum progesterone and luteininzing hormone monitoring 2) urinary progestagen monitoring 3) fecal progeatagen monitoring 4) bull behavioral response to female urine from various stage of estrous cycle, and compare with hormone profile of female. The first 3 methods are highly cost and not practical in the elephant camp situation. Three methods of serum progesterone and luteininzing hormone (LH) analysis, urinary progestagens evaluation and the male behavioral response to female urine are reliable for estrus determination, and will be implemented for the suitable breeding program of Thai elephant.