Controversy exists over levels of DNA integrity in the sperm of fertile and infertile men. In addition, the effect of leukocytospermia on sperm DNA in these 2 groups is unclear. We decided to address these questions by collecting semen samples from men known or presumed to be fertile and men from infertile couples. Samples were analyzed and assessed for sperm concentration, motility, and morphology. Samples failing to meet World Health Organization (WHO) standards in one or more of these parameters were judged abnormal. Samples were then arbitrarily assigned normalized scores in each of the above parameters, and scores were summed to give a normalized value for overall sperm quality. DNA abnormality was determined by an in situ DNA denaturation test with acridine orange and expressed as a percentage of cells with abnormal DNA integrity (ADI). Assessment of 187 samples revealed a moderate inverse correlation between ADI and sperm quality (r =.58), although a large degree of ADI dispersion was observed in abnormal semen samples. The average ADI for normal and abnormal semen samples was 18% +/- 2.8% and 36% +/- 5.8%, respectively, with the threshold of 95% probability set at 30%. When sorted for leukocytospermia, the difference in ADI between normal and abnormal semen groups without leukocytospermia was much smaller (17% +/- 2.2% and 22% +/- 4.6%; P =.023). Leukocytospermia had no significant effect on ADI in the normal semen group (P = .46); however, ADI was more than double the ADI in the abnormal semen group (18% +/- 2.4% and 50% +/- 11%; P < .001). The results of our analysis show that at least 3 factors affect net DNA integrity in leukocytospermic samples that fail to meet WHO standards: 1) primary DNA damage, which is moderately inverse to sperm quality, in particular to sperm concentration; 2) effect of leukocytes increasing primary or provoking potential DNA damage in a cascade-like manner, particularly in sperm with poor morphology and motility; and 3) a decreasing proportion of cells with damaged DNA in semen with the worst quality.