  Reconnection of the magnetic lines of force is considered in case the
magnetic energy exceeds the rest energy of the matter. It is shown that the
classical Sweet-Parker and Petschek models are generalized straightforwardly to
this case and the reconnection rate may be estimated by substituting the Alfven
velocity in the classical formulas by the speed of light. The outflow velocity
in the Sweet-Parker configuration is mildly relativistic. In the Petschek
configuration, the outflow velocity is ultrarelativistic whereas the angle
between the slow shocks is very small. Due to the strong compression, the
plasma outflow in the Petschek configuration may become strongly magnetized if
the reconnecting fields are not exactly antiparallel.
