The Gunung Halimun Reserve has the largest area of primary rain forest left on Java. The reserve is important for the habitat it provides for two endangered primates, the moloch Hylobates moloch and the grizzled langur Presbytis comata, which are endemic to western Java. The author presents the results of a survey conducted in the reserve in July 1989 and makes suggestions for further survey work and scientific research on the primates there.