Using a set of cotton samples representing differing growing times, the present paper assesses the potential of the Sirolan-Laserscan to measure average fibre fineness. The measured results accurately reflect the expected variations in fibre fineness values for these samples. Combining these measured fibre fineness values with HVI micronaire data the paper illustrates that average maturity ratio values can also be obtained. Again for the set of samples measured the average maturity ratio values follow the expected trends. Further an independent simple test is developed to examine the internal consistency of the fineness and maturity ratio values for this set of samples. The Sirolan-Laserscan results pass this test unlike those obtained from the FMT.