In this study, heat transfer and pressure drop characteristics of water/TiO 2 nanofluid flow inside a corrugated tube is investigated. The boundry condition is uniform wall temperature. For this purpose, a test apparatus was designed and assembled. The length of test section was 93 cm with internal diameter of 7.71 mm and outer diameter of 9.52 mm. First, the data were obtained for distilled water in the plain tube. Later, various test runs were performed for two nanoparticle concentrations ( =0.1%, 0.5%), two corrugation depth (e/d i =0.0648, 0.103), two corrugation pitch (p/d i =0.917, 1.297) and two corrugation width (w/d i =0.363, 0.492) in a wide range of Reynolds numbers (3000 Re 15000). Experimental results showed the experimental values of the Nusselt number and friction factor for the plain tube are in good agreement with the values predicted by empirical equation and the average deviation is about 3.25% and 7.3%, respectively. For distilled water and nanofluid flows, Nusselt number enhances with increasing Reynolds number. Also, adding nanoparticles causes heat transfer enhancement which is due to the increase in the thermal conductivity. As found, the nanofluid with TiO 2 concentrations of 0.1% and 0.5% volume gives mean Nusselt numbers higher than those of the base fluid around 1.6 and 3.4%, respectively. The heat transfer in transversely corrugated tube is more than that in helically corrugated tube. Also, Nusselt number enhances with the increase of corrugation depth and corrugation width (especially in larger Reynols numbers) and the decrease of corrugation pitch to diameter ratio. As can be seen, the effect of nanoparticles on heat transfer of corrugated tube with higher corrugation depth and corrugation width and lower corrugation pitch is further. The friction factor decreases with increasing Reynolds Number and increases with increasing volume concentration. The nanofluid with concentrations of 0.1% and 0.5% by volume gives mean friction factors higher than those of the base fluid by around 1.9% and 4.8%, respectively. Also, the friction factor in transversely corrugated tube is more than that of helically corrugated tube. and the friction factor increases with the increase of corrugation depth and decrease of corrugation pitch and corrugation width (especially in larger Reynols numbers). But, for all corrugated tubes, adding nanoparticles causes slight increases in friction factor compared with the plain tube in the range of present experiments. For all corrugated tubes the thermal performance factor, remains more than unity and increases up to about 6000 Re and then reduces. But with increase of corrugation width, thermal performance increases for Reynolds number more than about 12400. Also, this factor have better performance for higher corrugation depths and corrugation widths and lower corrugation pitches. Moreover, the highest performance is about 2.44 which achieved for 0.5% of nanoparticles concentration inside the corrugated tube with e=1.2 mm, p=7 mm and w=2.8 mm at Reynolds number of about 6000. Keywords: heat transfer, pressure drop, nanofluid flow, corrugated tube, uniform wall tempretur