Development of drugs targeting Bcl-2 relatives and caspases, for treating diseases including cancer and inflammatory disorders, often involves measuring interactions with recombinant target molecules, or cancer cell killing in vitro. We established a yeast-based method for evaluating drug-mediated inhibition of Bcl-2 relatives or caspases. Active Bax and caspases kill Saccharomyces cerevisae, and pro-survival Bcl-2 proteins can inhibit Bax-induced yeast death. By measuring the growth or ATP content of transformants co-expressing Bax with pro-survival Bcl-2 relatives, we showed that the anti-Bcl-2 drugs ABT-737 or ABT-263 abolished Bcl-2 or Bcl-xL function and reduced Bcl-w activity, but failed to inhibit Mcl-1, A1 or the poxvirus orthologs DPV022 and SPPV14. Using this technique we demonstrated that adenoviral E1B19k was also resistant to these agents. The caspase inhibitor Q-VD-OPh suppressed yeast death induced by caspases 1 and 3. Yeast engineered to express human apoptotic regulators enable simple, automatable assessment of the activity and specificity of candidate drugs targeting Bcl-2 relatives or caspases.