Pots experiments were conducted to study the effect of incubation period on the behavior of Cd, Pb and Ni in sandy, Nile alluvial and calcareous soils. The treatemnst were 0, 2.5, 5, 10 and 20 mg Cd kg-1 soil; 0, 50, 100, 200 and 400 mg Pb kg-1 soil; and 0, 5, 10, 20 and 40 mg Ni kg soil-1 in the forms of CdSO4, Pb(NO3)2 and NiSO4, respectively. The different soils were exposed to soil removable after 0, 7, 14 and 45 days of incubation for extracting the available Cd, Pb and Ni. The results shoed that increasing the levels of Cd, Pb or Ni added to the different studied soils was associated with a progressive significant increase in their availability. Increasing the time of incubation was accompanied by a gradual decrease in the available contents of Cd, Pb and Ni. Multiple regression analyses showed the importance of O.M and pH in influencing the avialabilty of Cd, Pb and Ni in different soils.