Stark widths and shifts for twenty-four lines of Sn II and three lines of Sn I have been measured and calculated. For the 8s-6p, 7p-5d, 7d-6p, 8d-6p and 5f-5d transitions in Sn II and 5p6s- in Sn I they are the first experimental values known. Measurements are carried out by observing the emission lines from an optically thin laser produced plasma from a tin target in Ar atmosphere. The electron temperature was close to K and the electron density . Calculations are based on the semiempirical method proposed by Griem with atomic matrix elements obtained by using the Hartree-Fock approximation including relativistic corrections and - - configuration interactions.