(1) In two areas of Bristol, one 5.5 km [²], the other 3.2 km [²] fox litter counts in two consecutive years were used to estimate the number of fox groups. There were 3.64 family groups/km [²] in the smaller. In parts of the larger area densities of 4-5 family groups/km [²] were recorded. (2) To obtain data on the distribution and relative densities of foxes throughout Bristol nearly 88,000 school children were asked to record fox sightings for a period of one month. Since the absolute fox densities were known for two areas the distribution of recorded sighting could then be used to estimate fox densities throughout the city. By this means it was calculated that there were 211 fox family groups I an area of 116 sq km, a mean density of 1.82 fox family groups/km[²]. (3) Fox distribution in the city was uneven, and fox density was not found to correlate with household density, housing type, age of housing stock, or an other obvious habitat feature. There was a negative correlation (P< 0.001) between the distribution of stray dogs and urban foxes. This was attributed of the fox population by stray dogs. It is suggested that disturbance may be particularly important in the breeding season; dogs were the second major cause of mortality in young fox cubs. (4) Based on post-mortem material, it was calculated that the ratio of breeding to non-breeding vixen was 1:0.35, and so the adult fox population consisted of 211 males, 211 breeding females and 74 barren females. Assuming that all fox family groups breed each year, with a mean birth litter size of 4.80 (calculated from placental scars), the annual cub production would be 1013. [ABSTRACT FROM AUTHOR]