This study evaluates the effects of temperature and aging on the efficacy of As(2)O(3) at the 45th decimal potency in a wheat germination model, compared against a control and potentized H(2)O 45×. Each treatment-temperature combination was tested on seeds (Triticum aestivum L.) of Pandas variety, using six Petri dishes (33 seeds/dish) per trial, performing eight trials. Seeds were pre-treated by poisoning with 0.1% As(2)O(3) solution to reduce germination, to allow a better evaluation of homeopathic treatment effects. The outcome variable was the number of non-germinated seeds after 96 h. Temperature effect was investigated by heating each treatment in a water bath for 30 min (at 20, 40 or 70°C), or for 5 min (at 100°C), and that of aging by dividing experimental data, collected over a period of nearly five months, into two groups: early and late experiments. Results seem to show that the efficacy of As(2)O(3) 45× is unaltered at 20 and 40°C, increases at 70°C and decreases at 100°C. As regards aging, a notable difference was found between early trials, with no significant efficacy, and late trials, where As(2)O(3) 45× exhibits a repeated significant effect versus control, except at 100°C. A reduction in variability was observed for As(2)O(3) 45× at 20°C versus control, confirming the findings of previous work. The main conclusion suggested by this experiment is that the efficacy of As(2)O(3) 45× on wheat germination may be influenced by heating degree and seems to have an increasing trend as a function of aging.