4-Amino-3,5-dichlorobenzaldehyde is an impurity of Clenbuterol (C569998, HCl) and is used as a reagent in the synthesis of pyrazolopyridine derivatives as inhibitors of phosphodiesterase-4 (PDE-IV) and production of tumor necrosis factor-α (TNF-α). 4-Amino-3,5-dichlorobenzaldehyde is also used as a reagent in the synthesis of amino acid derivatives as neuropeptide Y antagonists.