OBJECTIVE: To determine the effect of Matrigel at a low concentration on the growth of mouse embryos in culture. DESIGN: Randomized case-control study of mouse embryos. SETTING: An academic research environment. ANIMALS: Mouse embryos. INTERVENTION(S): Embryos were cultured in Quinn's or Celbio's human tubal fluid (HTF) enriched with 1.5% bovine serum albumin and 0.8% liquid Matrigel. Each HTF was compared with the same medium devoid of Matrigel. Afterward, Quinn's and Celbio's HTF, both containing Matrigel, were compared directly. Embryos were cultured in four-well dishes, and their morphology and viability were assessed at 96 hours. MAIN OUTCOME MEASURE(S): Level of interleukin-1alpha in media collected at the end of culture. RESULT(S): In both types of HTF, the presence of Matrigel allowed a larger number of embryos to reach the blastocyst stage and to hatch; blastocyst morphology also was improved. These positive effects were enhanced in Quinn's HTF: embryos cultured in its Matrigel-enriched version secreted a higher level of interleukin-1alpha than those in Celbio's HTF plus Matrigel and also showed a better morphology. CONCLUSION(S): In the mouse embryo model, Matrigel improves culture conditions in terms of both embryo viability and morphology, and these effects are enhanced in Quinn's HTF.