TUBE88 computes magnetic field lines in cylindrical or toroidal geometry (using cylindrical coordinates ( r, φ, z)) and calculates the intersections of those field lines with specified planes. It is an outgrowth of a code first written in 1967. A fourth-order predictor-corrector method is used to integrate the field line coordinates. The magnetic field may be computed in several ways: (a) through specification of currents flowing in very specific helical and circular elements together with a “1/ r” field and a vertical field, (b) as a Fourier series in the angular variale or (c) in a specific coordinate system suited to a toroidally helical domain. Extensive graphics are provided for users of the Cray Time-Sharing System (CTSS). Applications of the code have included analysis of vacuum magnetic field configurations and post processing magnetic field data produced by MHD codes, for example.