Theoretical and experimental studies of absorber switching efficiencies are described for a ruby laser operating at 77°K. The various operating regimes of absorber‐switched lasers are reviewed and the importance of inclusion in the theory of nonsaturable losses associated with the laser and absorber media is demonstrated. A particular dye‐host combination is found to have a markedly superior switching efficiency, the essential factor being a low residual loss under saturation conditions. The residual loss of vanadium phthalocyanine is shown to be host dependent and some tentative explanations of this are discussed.