The development of gypsum maze caves in hypogene settings is examined by process-based numerical modelling using a coupled continuum-pipe flow model. The model scenarios are largely based on field observations compiled from the gypsum karst terrain of the Western Ukraine. This area hosts the world's largest maze caves in gypsum and provides a well documented example of hypogene speleogenesis under artesian conditions. Building on previous studies that revealed the basic speleogenetic mechanisms in this type of setting, this work aims to examine the influence of the variability of the initial apertures on dissolutional growth of fissures and the evolving cave systems. To this end, the initial apertures were spatially uncorrelated and lognormally distributed and the influence of the coefficient of variation of the aperture data (σ/μ) was investigated in several scenarios on the basis of a set of four realisations. It is found that a small degree of heterogeneity leads to cave patterns similar to those obtained with uniform initial apertures. However, with increasing heterogeneity the karstification process decelerates and a significant amount of variability between the different realisations follows. In an ensemble average sense, the aperture variability is determining the temporal development of the cave patterns and generally decelerates the karstification process, but appears to be of minor relevance regarding the general structure and geometric properties of the evolving cave patterns.