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In African semi-arid savannas livestock production frequently dominates human activity, but it has been claimed that wildlife ranching can be more profitable than extensive beef production. Traditional accounting methods generally exclude the biological costs of stocking effects on rangeland productivity. This paper presents a framework for evaluating overstocking effects on the financial profits (based on market prices) and economic profits (estimated from the opportunity costs of inputs and outputs) of alternative range-based animal production systems. The method was applied to 50 commercial cattle, wildlife, and mixed ranches in the Zimbabwe Midlands using 1989/90 data. Level of overstocking was estimated from positive differences between grazer stocking rate and rangeland carrying capacity, which was predicted from long-term mean annual rainfall. Since it is generally impossible to accurately quantify stocking effects on rangeland productivity, and thus to confidently evaluate overstocking costs, values ranging from Z$0.00 to Z$0.50 kg-1 ha-1 overstocking were used. The resulting range of costs were subtracted from financial and economic profits. Cattle ranches were significantly overstocked while mixed and wildlife ranches were not. Thus cattle ranch profits decreased more rapidly with increasing simulated overstocking cost. In other words, with increasing sensitivity to overstocking, wildlife and mixed ranches had a higher probability of remaining financially and economically profitable than did cattle ranches.