AbstractThe circular dichroism of Ac–Ala–NHMe,cyclo(–Ala–Ala–), Ac–Ala–OMe, Ac–Ala–Ala–OMe, and Ac–Ala–Ala–Ala–OMe has been measured in water and in aqueous salt solutions as a function of temperature. Onlycyclo(–Ala–Ala–) exhibits circular dichroism which is independent of temperature. Each of the linear derivatives ofL‐alanine exhibits a positive circular dichroism in the range 208–218 nm at 15°C in water. Heating reduces the intensity of the positive circular dichroism, and only Ac–Ala–OMe retains positive circular dichroism at 75°C in water. Isothermal addition of salts produces changes in the circular dichroism of linear derivatives ofL‐alanine which resemble those seen on heating. The relative effectiveness of the salts tested, at a concentration of 4M, is LiCl ⩽ KCl = NaCl