This paper deals with the effects of accumulated timing-jitter on the signal-to-noise ratio (SNR) of real sine waves. Such a problem was recently investigated by the author, using the discrete-Fourier method. However, the frequency-domain analysis has some limitations due to the fact that some of the accumulated timing-jitter noise power, found at the fundamental frequency component, would be added to the power of the input signal itself. Thus, in this paper, the analysis is performed in the time-domain and is restricted to the SNR measurement. An expression for the SNR in terms of timing-jitter distribution parameters, and the number of samples of the input signal, is developed. Computer simulations are presented, which showed excellent agreement with the developed expression. Also, a comparison between the results obtained from the time-domain analysis and the frequency-domain, is presented.