We examined the frequency distributions of worm burdens and worm biomass of the dominant gastric nematode, Protospirura muricola, of eastern spiny mice (Acomys dimidiatus) surveyed at 4-year intervals over a period of 12 years in two montane wadis in St. Kathrine's Protectorate in S. Sinai, Egypt. Whilst the frequency distribution of worm burdens differed significantly between the mice from the 2 wadis, variation between years was not significant among mice from each wadi. The frequency distribution of P. muricola worm burdens did not differ significantly between the sexes, despite female mice carrying significantly higher worm burdens, but showed a marked difference between juvenile and mature mice. The biomass of P. muricola carried by individual mice varied considerably, with two mice from Wadi Gharaba carrying biomasses of over 1 gm, representing over 2.5% of total body weight. Biomass showed significant positive covariation with worm burdens, and heavy biomass and worm burdens were most likely among the older mature female mice. The frequency distribution of individual worm weights indicated that frequent low-dose transmission was common, with rarer instances of higher-dose, package transmission from insect vectors of this parasite.