The m i n i m u m value rtmin of the interaction index c o m patible wi th unstable oscillations in a liquid rocket is advanced as the basic criterion of uncondit ional stability of the system. For systems wi th known constants of the feeding system components , the value of nmin is given explicitly in terms of these constants . For any arbitrary system for which the constants of the feeding system c o m ponents are n o t easily evaluated, the value of nmin of such systems can be obtained directly from certain flow tests of the over-all feeding system. If the interaction index n of the propellant is less t h a n this nmin, the system is u n conditionally stable regardless of the magni tude of the t i m e lag of the system. Any change i n t h e design of the feeding system of certain component constant leading to a larger nmin is stabilizing. The effects of several cons tants are briefly discussed. In particular, the transfer funct ion of the feedback circuit of a servomechanism actuat ing a control capacitance next to the injector tha t will make a given system uncondit ional ly stable is given explicitly i n terms of these constants for both monopropel lant and bipropellant systems.