At Auschwitz, Wirths was known to be protective of prisoner doctors and other prisoners doing medical work, to have improved conditions on the medical blocks and was remembered favourably by most prisoner doctors and other inmates who had contact with him. At the same time, Wirths in recommending Dr. Josef Mengele for promotion in August 1944, was able to speak of Mengele's "open, honest, firm … absolutely dependable" character and "magnificent" intellectual and physical talents; of the "discretion, perseverance, and energy with which he has fulfilled every task … and … shown himself equal to every situation"; of his "valuable contribution to anthropological science by making use of the scientific materials available to him"; of his "absolute ideological firmness" and "faultless conduct [as an SS officer"; and personal qualities as "free, unrestrained, persuasive, and lively" discourse that rendered him "especially dear to his comrades".