A survey is given of the assassin bugs (Reduviidae) collected on the six Netherlands Antilles. All together 22 species were sampled: 6 Emesinae, 1 Saicinae, 8 Harpactorinae, 1 Piratinae, 4 Stenopodinae, 1 Triatominae and 1 Phymatinae. Sixteen species were captured on the three islands of the Leeward Group, Aruba, Curaçao and Bonaire; seven species were found on the three islands of the Windward Group, St. Eustatius, Saba and St. Martin; both groups of islands have only 1 species in common. The local distribution of the species represented (Table 1) does not fit with their known gross distribution in the neotropics. Curaçao harbours more than 70% of the total number of species; zoogeographical aspects have been discussed. Two species are described as new; Cosmoclopius curacavensis (Harpactorinae), living on Curaçao as a predator exclusively on the weed Cleome viscosa, and Oncerotrachelus sabensis (Saicinae) from Saba. The identity of some Emesinae and the single phimatine specimen captured remain unsettled for the present. Triatoma maculata. vector of a T. cruzi strain with low virulence, occurs in two colour forms; the dark one restricted to Aruba, the light-coloured form to Curaçao and Bonaire. Total drawings of most species are presented in addition to some 120 figures of structural details of eggs, larvae and adults. Features of eggs and genitalia are discussed on pages 17-28. Some points of general interest are: The egg of Sinea coronata appeared to be quite different from what is known from other Sinea spp. Eggs of Piratinae have movable slips with plastron function. The harpactorines Atrachelus fuscus and Sinea coronata lack parameres. Behavioural aspects concerned with utilizing sticky material have been summarized. Evidence is presented that the subrectal gland, occurring in many Harpactorinae, secretes the colleterial liquid for the egg-batch. The asymmetrical genitalia of the Piratinae and the endosomal brush zone and basal differentiation of the ductus ejaculatorius in some Stenopodinae are stressed.