The micronaire measurement is a mixture of both fibre fineness (mass per unit length) and maturity. By comparison, the fineness of wool samples has, for many years, been determined using an airflow technique similar to that used for the micronaire measurement. Recently, CSIRO Wool Technology developed a new commercial instrument, the Sirolan-Laserscan, for the rapid measurement of the full fibre diameter distribution of wool samples. This preliminary project was designed to assess the potential of the Sirolan-Laserscan, in a new mode of operation, to measure cotton fineness independently of maturity. Thirteen cotton samples whose fineness and maturity values had been measured previously using the Shirley Fineness and Maturity Tester were used. These samples covered a broad range of both fineness and maturity values. A good correlation was found between the average fibre fineness measured by the Laserscan and the previously reported values.