In vitro cytotoxic and genotoxic effects of donkey milk on cancer (A549) and normal (BEAS-2B) lung cell lines were investigated. The XTT and WST-1 tests as well as clonogenic assays were used to evaluate cytotoxicity. The comet assay and micronucleus test were used as genotoxicity endpoints. Donkey milk showed lower cytotoxic effects against normal lung cell line BEAS-2B in comparison to the tumor cell line A549. Genotoxicity experiments revealed dose dependent increases in the frequencies of micronuclei and single stranded DNA breaks in A549 cells whereas no significant damage was observed in BEAS-2B cells. The results indicate that donkey milk has anti-proliferative and genotoxic effects on lung cancer cells at concentrations which are non-toxic to normal lung cells.