The prevalence of intestinal parasites in domestic cats from the London area was surveyed over an 18-month period by microscopic examination of faecal samples. Of the 947 cats examined 11.5 per cent were infected with Toxocara cati, 1.9 per cent with Isospora felis, 1.2 per cent with Dipylidium caninum, 1.2 per cent with Taenia taeniaeformis, 0.8 per cent with I rivolta and 0.2 per cent with Toxascaris leonina.