Seventeen novel nitrosourea anticancer structures (2 to 18) obtained from substructure and similarity search analysis applying lomustine as parent structure are presented for comparison. The structures are substantially diverse by substituent following the nitroso (R–NO) and urea group OC. Other notable substituent aspects include aliphatic carbon chains, double-bond carbon chains, hydroxyl (–OH) groups, halogens (Cl and Br), and ring structures.