Eggs were collected from Hy-Line brown flocks aged 33, 50 and 67 wk. Thirty eggs from each flock were analyzed to determine the reliability of MST (MS Technologies, U.K.) cuticle blue stain as an indicator of the presence of cuticle and the effective removal of cuticle by use of an EDTA solution. Another 30 eggs, collected at the same time from each flock, were processed for the quantification of protoporphyrin IX (PP IX) from the eggshell with and without the presence of cuticle. The L*a* components of the colour space system were significantly different among the age groups. There was a high degree of correlation between the extent of MST cuticle blue staining and the amount of cuticle on the eggshell as recorded by scanning electron microscopy. PP IX pigment was quantified by spectrophotometric analysis of digested eggshell solutions.