Experiments were conducted to investigate the effect of pulsation upon heat transfer characteristics for fully-developed turbulent flow downstream through heated circular pipe. The Experiments were conducted with an electrically heated horizontal brass tube (40 mm inner diameter and 3000 mm long) under constant heat flux, with air as working fluid. The Experiments were carried out for Reynolds number range of 27925 to 58854 and pulsating frequency range of 45 to 145 Hz. The results showed that the relative average Nusselt number is increased as both Reynolds number and frequency increases and the enhancement in heat transfer depending on both frequency and Reynolds number. As frequency increases for 45 ≤ ƒ ≤ 145 Hz, the relative average Nusselt number increases and peaks at frequency of 45 Hz for Reynolds number of 55534 with about 84.5% enhancement obtained. The results showed that the heat transfer was highly affected by Reynolds number while it was lightly affected by the pulsating frequency.