Two widely used methods for capturing bats away from their roosts are mist nets and harp traps (Kunz and Kurta, 1988; Tuttle, 1974). In Australia, Tidemann and Woodside (1978) found that harp traps were about 10 times more effective than mist nets at catching small to medium-sized vespertilionids and rhinolophids. In Costa Rica, Laval and Fitch (1977) found that traps were about 1.7 times as effective as nets. However, there is some evidence of variation among species in their susceptibility to traps. Laval and Fitch (1977) reported that large phyllostomids frequently were caught in mist nets and rarely were trapped, whereas the reverse was true for several small vespertilionids. Such interspecific variation in susceptibility can affect the choice of capture methods for a particular study, and must be considered in community studies if the number of captures is used as an index of relative abundance of species (Fleming, 1986). In this paper, I compare the effectiveness and selectivity of mist nets and harp traps in the understory of Malaysian rain forest. I also compare the relative success of two different designs of harp traps. The original harp traps had a single bank (row) of wires and were effective for capturing fast-flying bats such as molossids, but not for more maneuverable species (Constantine, 1958). Subsequently, traps with two banks of lines were used widely (Tidemann and Woodside, 1978; Tuttle, 1974), but even these may capture less than half the bats encountering them (Kunz and Anthony, 1977). I developed new designs of harp traps with additional banks of lines, and present here data on the trapping efficiency of four-bank traps compared with two-bank traps. The study was conducted between 1981 and 1987 in two areas of lowland rain forest in Malaysia: Pasoh