L-carnitine is required during the oxidation of lipids for the transport of fatty acids from the cytosol into the mitochondria for generation of energy. L-carnitine exerts a substantial antioxidant, anti-cytokines and anti apoptotic actions providing multi-mechanisms protective effects for the cell. The gametes in vitro may be exposed to damaging effects from oxidative stress (OS) due to either the high oxygen tension compared to the in vivo condition or the preparation producers preceding the in vitro fertilization (e.g. sperm preparation procedures preceding the in vitro fertilization). Moreover OS can affect the gametes in vivo under certain conditions as in endometriosis or leukocytospermia. Oxidative stress and cell apoptosis may adversely impact the fertilization process and the subsequent embryo development and pregnancy outcome. This review discusses the protective effects of L-carnitine for gametes and embryos and how it may help improve the embryogenesis and the in vitro fertilization outcome.