A total of three drop-counting rain gauges are in operation inside the meteorological garden at the Hong Kong International Airport for rainfall measurement. The performance of this kind of rain gauges in terms of the local random errors is studied using the data collected for 15 months. To the knowledge of the authors, this is the first time that the local errors of drop-counting rain gauges are examined in an operational environment. The local error characteristics turn out to be rather different from the tipping bucket rain gauges. The standard deviations of the relative errors among the three drop-counting rain gauges are in general larger than those of the tipping bucket rain gauges as revealed in a previous study (Ciach, 2003). Their values at high rainfall rates (10 mm/hour or higher) are basically independent of the time-scale of rainfall accumulation. The implications of these results to the operational use of the kind of drop-counting rain gauge under study would be discussed.