Climate change and climate variability induce uncertainty in yields, and thus threaten long term economic viability of rain-fed agricultural enterprises. Enterprise mix diversification is the most common, and is widely regarded as the most effective, strategy for mitigating multiple sources of farm business risk. We assess the potential for enterprise mix diversification in mitigating climate induced variability in long term net returns from rain-fed agriculture. We build on APSIM modelling and apply Monte Carlo simulation, probability theory, and finance techniques, to assess the potential for enterprise mix diversification to mitigate climate-induced variability in long term economic returns from rain-fed agriculture. We consider four alternative farm enterprise types consisting of three non-diversified farm enterprises and one diversified farm enterprise consisting of a correlated mix of rain-fed agricultural activities. We analyse a decision to switch from a non-diversified agricultural enterprise with the highest expected return to a diversified agricultural enterprise consisting of a mix of agricultural enterprises. Correlation analysis showed that yields were not perfectly correlated (i.e. are less than 1) indicating that changes in climate variables cause non-proportional impacts on yield production. We conclude that at best, diversification can reduce the standard deviation of net returns by up to about A$110 Ha-1, or 52% of mean net returns; increase the probability of below-average net returns by up to about 4% and increase the mean of 10% of worst probable annual net returns by up to A$54/ha. At worst, diversification can reduce the mean of net returns by up to about A$95 Ha-1, or 46%.