(Abstract)This study was carried out to examine the effect of the difference in horticultural therapy on the vocational rehabilitation and physiological change of the intellectual disabilities. The general characteristics of work of intellectual disabilities show the restriction in the ability to acquire skills and difference, depending on the time and the number practice by individual. And the speed of forgetting is fast, and the transference and generalization of the learning fall behind. Therefore, this study was conducted through application of systematic prompt, simple and repetitive horticultural program and the analysis of the program in order to teach the horticultural works to the intellectual disabilities.Pressed flower program, planting program, flower decoration program, topiary program were carried out for the intellectual disabilities who were trainable from January 2007 to January 2009, which aimed to help improve their vocational rehabilitation, that is the function of hand, vocational skill, social skill, and emotional behavior. Based on the evaluation of the function of hand, the pressed flower program was effective for the left hand(P=0.009) and the right hand(P=0.001) in the case of the power at the finger tips. The flower decoration program was effective for right hand(P=0.020) in the case of grip power while, the topiary program was effective for right hand(P=0.019). The planting program was effective for right hand(P=0.028) for the wrist power, while the topiary program was effective for the right hand(P=0.019) and the left hand(P=0.003) for the wrist power. Based on the evaluation of the vocational skill, the planting program P=0.015), flower decoration program(P=0.001), and topiary program(P=0.005) brought about significant improvement in terms of the physical ability relating to the sub-items. Topiary program(P=0.031) brought about the significant improvement in terms of the vocational behavior relating to the sub-item. Based on the evaluation on the social skill, significant improvement was attained through all programs: press flower (P=0.043), planting(P=0.014), flower decoration(P=0.020), topiary(P=0.033). Based on the evaluation of emotional behavior, significant improvement was attained through all programs: press flower(P=0.000), planting(P=0.002), flower decoration(P=0.022), topiary(P=0.005).Based on the evaluation of the heart rate variability, significant difference was shown in the press flower in the case of SDNN item(P=0.008), the planting program in the case of SDNN(P=0.040), RMSSD(P=0.001), TP(P=0.007), LF(P=0.038), HF(P=0.006), and the flower decoration program in the case of LF(P=.047), and topiary program in the case of RMSSD(P=0.022), TP(P=0.033). The planting program showed the highest change in RMSSD and HF, the indexes showing the parasympathetic nervous system.The analysis of cortisol hormone indicated that the press flower program did not show any significant difference before and after the program, considering that it was 8.58nmol․L-1before the program, 4.66nmol․L-1 in the second test, and 7.56nmol․L-1 in the third test. It was measured 4.64nmol․L-1 in the fourth test and declined even further by 3.94nmol․L-1, which was a significant decrease than before the test. In the planting program, it was 11.92nmol․L-1, before the horticultural program, 9.86nmol․L-1 in the second test, and 9.74nmol․L-1 in the third test. It was measured, a decrease 3.08nmol․L-1 by than before the test and decreased significantly gradually compared to the period before the test. In the flower planting program, it was measured 10.06nmol․L-1 before the horticultural program, measured 9.4nmol․L-1in the second test, and 9.68nmol․L-1 in the third test. It declined by 1.46nmol․L-1in the fourth test, but no significance was found although the number declined in comparison to the period before the test. In the topiary program, it was measured 9.98nmol․L-1before the topiary program, and 7.0nmol․L-1 in the second test, a decrease by 2.28nmol․L-1, showing a significance difference. It was measured 7.16nmol․L-1 in the third test and 7.0nmol․L-1in the fourth test, showing a significance difference compared to the period before the test was carried out. In that way, the cortisol level which decreased significantly was maintained constantly after the implementation, unlike other programs. The aforesaid findings indicate that the press flower program, planting program, flower decoration program, and topiary program are effective for the intellectual disabilities to improve their physical, vocational, social skills and emotional behavior. And each program was effective in stimulating autonomic nervous system and reducing cortisol level. Therefore, effective vocational rehabilitation program may be realized if the horticultural program is planned which suites the characteristics of the intellectual disabilities based on the findings of this study.