Di-(C(7)-C(9) alkyl) phthalate (D79P) and di-(C(9)-C(11) alkyl) phthalate (D911P), based on high-normality linear oxo-alcohols, have been assessed for their impact upon reproductive performance in Sprague-Dawley rats. Rats were continuously exposed to either D79P or D911P at dietary levels of 0%, 0.1%, 0.5%, or 1.0% over two generations. Selected F(0) offspring (F(1) generation) were exposed to the same dietary concentration of D79P or D911P as the respective F(0) animals, and were mated to produce F(1) offspring. Both D79P and D911P markedly reduced body weight gain in F(0) and F(1) adult males at the highest dose, but females were affected to a lesser extent. There was no impairment of fertility, fecundity, or development in either generation, but body weights of offspring in the 1.0% D79P and 1.0% D911P groups were slightly and transiently reduced over the weaning period. Although decreases in the weight of several organs were accounted for by depressed body weight, ovary weights were reduced in both generations exposed to 1.0% D79P, and epididymidal weights were slightly reduced in adults of both generations exposed to 1.0% D911P. However, ovarian function-assessed by the oestrus cycle and mating behaviour-and epididymidal sperm concentration, motility, and morphology were unaffected by either substance. Treatment resulted in liver changes, particularly in males, characterised by increased liver weight in young animals, histopathologic changes and reduced organ weight in mature animals, and an increase in palmitoyl CoA oxidase activity. In conclusion, neither D79P nor D911P impaired reproductive function in rats when administered in the diet at levels that induce systemic toxicity, and the NOAEL for effects on reproduction in the rat is 0.5% for both D79P and D911P.