The available data dealing with boiling incipience of water in microtubes (tubes with diameters in the 0.1-1 mm. range) are analyzed. Macroscale models and correlations appear to under predict the heat fluxes that lead to the boiling incipience in microtubes. It is suggested that boiling incipience in microchannels may be controlled by the thermocapillary force that tends to suppress the microbubbles that form on wall cavities. Accordingly, a semi-empirical method is proposed for predicting the boiling incipience in microtubes. The effect of the turbulence characteristics of the microtube on the proposed method is also examined.