Analysis of testability of a class of low capacitance full-swing BiCMOS logic circuits is presented in this paper. It is shown that the stuck-open faults in the bipolar drivers of these circuits are masked by the additional MOS devices used to obtain full output logic swing. However, the stuck-open faults in the MOS devices are detectable by two-pattern tests as in standard CMOS. All single stuck-on faults result in significant increment in IDDQ when sensitized. Therefore, like static CMOS, these faults can be detected by IDDQ testing.