Reliable and automatic estimation of the Glottal Closure Instant (GCI), also referred to as epoch or pitch-event, has increasingly become an essential requirement in many speech processing applications, such as high-quality speech synthesis [1][2] and speech coding [3]. Although several methods exist [4][5][6], GCI detection still remains a difficult task. In this paper a robust pitch-event detection algorithm based on the sinusoidal modelling of speech is proposed. The improvement in performance over other well-known epoch detectors demonstrates the powerfulness of the sinusoidal technique for GCI determination.