We report the discovery of WASP-38b, a long period transiting planet in an eccentric 6.871815 day orbit. The transit epoch is 2455335.92050 +/- 0.00074 (HJD) and the transit duration is 4.663 hours. We performed a spectral analysis of the host star HD 146389/BD+10 2980 that yielded Teff = 6150 +/- 80 K, log g=4.3 +/- 0.1, vsini=8.6 +/- 0.4 kms, M* = 1.16 +/- 0.04 Msun and R* =1.36 +/- 0.05 Rsun, consistent with a dwarf of spectral type F8. The radial velocity variations and the transit light curves were fitted simultaneously to estimate the orbital and planetary parameters. The planet has a mass of 2.71 +/- 0.07 Mjup and a radius of 1.08 +/- 0.05 Rjup giving a density, rhop = 2.2 +/- 0.3 rhoJup. The high precision of the eccentricity e=0.032 +/- 0.0045 is due to the relative transit timing from the light curves and the RV shape. The planet equilibrium temperature is estimated at 1311 +/- 45 K. WASP-38b is the longest period planet found by WASP-North and with a bright host star (V = 9.4 mag), is a good candidate for followup atmospheric studies.
