The distribution of two stages of the nematode Labiostrongylus longispicularis (Wood) in thirty-eight stomachs of the Red Kangaroo, Megaleia rufa (Desmarest) has been analysed statistically.

A quadratic regression was used where y = log of mean worm densities of stomach sections + 1 and x = numerical values of the mid-positions of the sections. The analysis revealed significant maxima in the proximity of the cardiac region. The maxima in stomachs with relatively large numbers of worms were found to be further away from the pylorus than in the stomachs with small numbers of worms. The mean maximum densities were about fifty worms per 100 g of stomach content in highly infected animals and about eight in low infections. It is suggested that freshly chewed food or saliva may be a factor regulating the distribution of worms.

The parasite was absent from the stomach's pyloric region where the pH is low.

Sex and size of the worm were independent of its position in the stomach.

The average number of eggs per adult female in the different stomach sections roughly corresponded to the density of worms in these sections, but the sample material was inadequate to show that this relationship was statistically significant.

The mean number of fertilized eggs per female worm was 3300.

Thanks are due to Professor E. J. Williams of the University of Melbourne and Mr B. V. Fennessy of the Division of Wildlife Research, C.S.I.R.O., for reading and criticizing the manuscript, and to Messrs E. R. Hesterman and C. Kogon for technical assistance.