Epidemiological association between chronic exposure to pesticides and recorded cases of human malignancy in Gaza Governorates during the years 1990-1999 was studied. The pesticide usage in Gaza Governorates was recorded in detail. It ranged from 216.9 to 393.3 t from 1990 to 1999, respectively. Banned and extremely hazardous pesticides are identified according to their carcinogenicity, genotoxicity and cytotoxicity. Hospital cases of cancers in men and women were recorded. Each tumor type was grouped according to sex and age group from 0 to > 65 years. Total cases recorded in males were 2277, with average annual incidence and age-adjusted rate/100,000 was 53.2 and 96.8 respectively, whereas the total for females was 2458 cases, average annual incidence and age-adjusted rate/100,000 was 59.7 and 105.3, respectively, over the same 10 years. Lung cancer, lymphomas, leukemia, cancers of the urinary bladder, prostate, brain, colon, stomach and liver were the most abundant among males, while breast cancer, leukemia, lymphomas, cancers of the brain, uterus, lung, thyroid gland and liver were the most abundant in females. Statistical analysis using correlation coefficients and P values showed highly significant positive correlations between the type of pesticide and cancer incidence for male, female and both sexes. Correlation coefficients and P values, respectively, for both sexes were: 0.992 and 0.000 for insecticides; 0.952 and 0.000 for fungicides; 0.812 and 0.004 for herbicides; 0.925 and 0.000 for nematicides; 0.992 and 0.000 for others; and 0.994 and 0.000 for all types of pesticides. In the densely populated agricultural areas, it is not possible to separate or differentiate between occupational and general public exposure. Consequently, the introduction of and heavy use and misuse of pesticides and other toxic substances in the Gaza environment is suspected to correlate with the growing incidence of cancer. Precise determination of the effects of chronic exposure is, therefore, urgently needed. Future legislation to stop and regulate the use of extremely hazardous compounds will be essential. Continuous records for chronic diseases and cancers are also required for future follow-ups and periodical risk-assessment evaluations. Hence, further epidemiological studies are needed with detailed exposure assessment for individual pesticides, taking measures to reduce risk into consideration.