A study was conducted to determine the concentration of p,p[superscript]'-DDE in human milk and to examine various factors that affect the organochlorine pesticide residue concentration in human milk fat in 184 individuals from various population groups living in the urban area of Johannesburg, South Africa. The volunteers were apparently healthy primaparous and multiparous women breast-feeding healthy singleton infants. Data collected by personal interview included demographic information, and information pertaining to parity, previous breast-feeding experience, cigarette smoking habits, pesticide usage, food habits, drug usage, and alcohol consumption. Height and weight were also measured. Body mass index (BMI) was calculated. One full expression of breast milk from each individual was collected in the morning using an Egnell electric breast pump. Each sample was analyzed for total fat content and p,p[superscript]'-DDE concentration in human milk fat. DDE concentration in whole human milk was calculated. The mean concentration of p,p[superscript]'-DDE in human milk was 1.1 ± 1.1 mg/kg fat, which is comparable to other Western countries and those in the Global Environmental Monitoring System (GEMS). Significant differences (p < 0.05) in the concentration of DDE mg/kg fat were found among the different population groups when 2 high values were removed. The mean concentration of DDE in human milk for White, Colored, Black, and Indian donors was: 1.30 ± 0.14 mg/kg fat, 1.00 ± 0.14 mg/kg fat, 0.90 ± 0.10 mg/kg fat, and 0.76 ± 0.42 mg/kg fat, respectively. The mean total fat content was similar among the various population groups. There was no evidence that the concentration of DDE in human milk fat was affected by cigarette smoking habits, pesticide usage, residence of the donor, or alcohol consumption. There was evidence of factors contributing to the concentration of DDE in human milk fat among all donors and/or within certain population groups; these were age, parity, total accumulative time of previous breast-feeding, BMI, fat content, food consumption patterns, and steroidal contraceptive usage.