The patients who were diagnosed as pediatric malignancies in the Depar
tment of Pediatric Hematology of Uludag University Medical Faculty (Bu
rsa, Turkey) were analysed. The increase of acute leukemia (AL) betwee
n 1986 and 1993 is found significantly high. The maximum increase is d
etermined in this group in 1991. The increase of lymphoma and other so
lid tumors group after 1986 is not found significant. The authors can
not directly relate the increase of AL to the atmosphere contamination
by radioactive elements after Chernobyl accident because the other en
vironmental causes can not be ruled out.