The global production of CH4 from wild ruminants is dificult to estimate due to lack of sufficient data on animal populations and feed intake. Some population assessments exist, however, for certain regions of the world and can be extrapolated to global conditions. McDowell (1976) gives a population figure of 27 million for wild ruminants in the northern temperate regions (except China). These ruminants are comprised mostly of deer and moose. In Table 2, we have listed their mean body size (Nowack and Paradiso, 1983) and feed intake (e.g. Nystrom, 1980; Sadleir, 1982). As wild ruminants live entirely on roughage and herbs near maintenance levels, we assume a CHI yield of 9%. Using these figures, we obtain a total release of 0.4 Tg of methane by wild ruminants in the temperate regions, mostly from deer. Information on populations and mean body weights of wild ruminants in the Serengeti is summarized in Table 3 (Houston, 1979; Western, 1979). The total population of about 2 million mainly consists of gazelle and wildebeest. Data on gross energy intake in Table 3 have been calculated from formula (1) for the basal meta- bolic rate, multiplied by a factor of 2 to give the likely gross energy requirement of free living ungulates (Moen, 1973; Eltringham, 1974). Again, 9% of the gross energy intake is assumed to be released as methane. With this information, the CH, production in the Serengeti from ruminants is estimated to be about 0.02 Tg per year. Assuming the CH, production in the Serengeti to be representative of global conditions, the total CHI production by the wild ruminant population of 100-500 million in the subtropical and tropical regions (McDowell, 1976) may be estimated to be of 1-5 Tg per year. Together with the contribution from ruminants in the northern temperate regions, the annual CH, production from wild ruminants in the world may, therefore, be equal to 24 Tg per year which is small compared to the CH, production by domestic animals. Statistics on methane production by other large, non-ruminating herbivores in the Serengeti are likewise listed in Table 4. The most important contributions come from zebras and elephants. The total methane production is less than 10% of that by the ruminants. Altogether, non- ruminating large herbivores are a negligible source of atmospheric methane.