The slug, Laevicaulis alte, is a vector of Angiostrongylus cantonensis in the Greater Bombay area. The seasonal prevalence of A. cantonensis was investigated to determine the maximum intensity of the parasite in a field population occupying an area of approximately 400 m2. The maximum intensity of larvae was observed in the rainy months, June-November. Investigations showed that individual L. alte could tolerate an infecting dose of 150 first-stage A. cantonensis larvae before mortalities occurred.