The “standardless” quantitative phase analysis method proposed by Rius, Plana, and Planques [J. Appl. Cryst. 20, 457 (1987)] was evaluated by applying it to two series of artificial samples. The method was then applied to determine quantitatively the phases present in six different natural kaolin samples from Egypt. Two kaolinite peaks were selected for this analysis: One of them is known to be affected by stacking disorder, the other one is the 001 basal reflection, which is not significantly affected by stacking disorder. The method was also applied to samples of different mesh sizes. The results obtained when using the basal reflection showed that Egyptian kaolin is mainly kaolinite (82%–95%) together with anatase (2%–9%), rutile (1%–6%), and quartz (0.5%–7%). These analyses agreed very well with those obtained by chemical analysis. On the other hand, the analyses of the phases obtained from the peak which is strongly affected by stacking disorder were totally different. It was found also that by decreasing the particle sizes of kaolin samples the phase abundance of kaolinite increases, whereas those of quartz and anatase decrease. The results showed also that the standardless method is only applicable to peaks that are not strongly affected by structural disorder.