Direct shear test results with Mikasa's apparatus are presented for Ariake (Japan), Bothkennar (U. K.), Champlain (Canada) and Drammen (Norway) clays which are representative soft marine clays in the world. Direct shear strength of the four clays measured both in the normally consolidated state and in the field state are indicated and discussed together with stiffness. In addition, distribution patterns of the in-situ shear strength and various shear strength from unconfined commpression, field vane and cone penetration tests are shown.