Vibration response of a long flexible horizontal cylinder having pretension in water flow is very complex. Some phenomena which were still not clearly understood have been found in its motion behavior. This paper presents experimental results of a long flexible horizontal cylinder have been towed in still water which is free to respond in both, in-line and transverse directions. The length-to-diameter ratio of the test model was around 269 with a mass ratio of 1.7. Reynolds number varied from 9 × 102 up to 4.5 × 103. The model was positioned in two angles of 0 and 5 degree in horizontal plane which respect to the fluid flow. Pretension was applied to the test cylinder for towing speed of 0.1 up to 0.5 m/s in each case of the test. The motion data were recorded as digital image data using some CCD cameras and were analyzed using image processing technique. The frequencies of the CF (cross-flow) VIV response follow the Strouhal frequencies for a constant Strouhal number (St = 0.166) for both cylinder position, θ = 0 and θ = 5 degree respectively. It was found that multi-mode responses occurred at higher flow velocities. Further analysis will be done and additional results will be published later.