The in vivo toxicity of new metallodrugs either as Small Bioactive Molecules (SBAMs) or Conjugates of Metals with Drugs (CoMeDs) or their hydrogels such as with hydroxyethyl-methacrylate (HEMA) (pHEMA@SBAMs or pHEMA@CoMeDs) are evaluated by the brine shrimp assay. Thus individuals of Artemia salina larvae are incubated in saline solutions with SBAMs, CoMeDs, pHEMA@SBAMs or pHEMA@CoMeDs or without for 24 h. The toxicity is then determined in terms of the mortality rate of brine shrimp larvae. Brine shrimp assay is a low cost, safe, no required feeding during the assay, while it requiring only a small amount of the tested agent.