Abstract: Abstract Using binomial distribution fitting and poisson distribution, a survey of human intestinal parasitic infections in 115 sites of Hebei Province with a coverage of 65 803 residents in 18 234 families was pursued to observe family clustering of the infections. The result showed that the infections of Ascaris lumbricoides , hookworm, Enterobius vermicularis, Trichuris trichiura, Entamoeba histolytica and Giardia lamblia showed obvious family clustering. Analogous habits in daily life and production are deemed to be important factors in clustering of parasitic infections in families.