PURPOSE: To provide a modified polyethylene compsn. which has a density, a melt index and a solution viscosity within a specified range and is suitable for use in extrusion coating, by mixing a radical-generating agent with a linear medium/low density polyethylene and melt-kneading the mixture.

CONSTITUTION: 0.001W0.1wt% radical-generating agent such as di-t-butyl peroxide is mixed with a linear medium/low density polyethylene. The mixture is uniformly melt-kneaded at a temp. not lower than the melting point of said polyethylene to obtain the desired extrusion-coating resin compsn. The resultant compsn. has a density of 0.9W0.94g/cm3, a melt index of 3W30g/10min and a solution viscosity (ηsp/c) of a mean value between a and b obtd. from equations I and II. This compsn. is extrusion-coated on various substrates to obtain laminates having excellent strength, etc.