The B2Σ+_X2Σ+(0,0) and (1,0) bands of Tin between 410.3 and 427.3 nm were recorded using high resolution laser induced fluorescence (LIF) spectroscopy and these bands have been rotationally analysed. No rotational perturbation was detected in the (0,0) hand, however, four rotational perturbations have been found in the (1,0) hand. These per-turbations could be ascribed to a 4Σ+ perturbing state interacting with the B2Σ+ state. Least-squares fits of the line positions observed yielded molecular constans for the v=0 and 1 level of the B2Σ+ states, and the per-turbing 4Σ+ state.