1) An experiment was done with regard to the isolation from soil of the eggs of root-knot nematode (Meloidogyne incognita var. acrita Chitwood) by the centrifugal-flotation technique. 2) The percentage of eggs recovered in ZnSO_4 solutions of various specific gravities was 27.3% with the solution having a specific gravity of 1.12, and the highest percentage was 92.7% with the solution having a specific gravity of 1.40. 3) The percentage of eggs recovered from soil which involved free eggs was above 80% with the solutions having specific gravities of 1.36 and 1.40 in sandy soil, but it decreased gradually with different types of soil, that is, sandy loam, loam and clay. With clay soil, the percentage of the eggs recovered was about 70% with the solution having a specific gravity of 1.40. 4) The percentage of eggs recovered from soil which involved egg-masses was 80% with the solution having a specific gravity of 1.40, but it differed severely in other types of soil, and the percentage of eggs recovered from clay soil was about 46% with the solution having the same specific gravity. 5) The percentage of the eggs recovered by the first isolation and the second isolation from the same sample was very higher with the former isolation than the latter, but when the total percentage of both isolations was low, the percentage of the eggs recovered by the second isolation increased a little. 6) By the experiment which compared the number of the eggs recovered by the centrifugal-flotation technique with that of the hatched larvae recovered by the Baermann funnel technique, it was known that the number of eggs was greater than that of hatched larvae in any type of soil, particularly in sandy soil.