The aim of this study was to determine the association of estrous expression and successful embryo transfer (ET) and collection. In Experiment 1, Holstein heifers (10.5 to 14.5 mo) were superovulated (n = 69 from 51 animals) for the collection of embryos using a protocol based on FSH and progesterone. On the day of estrus, the total number of follicles present on both ovaries were counted via ultrasonography. On d 7 post-AI embryos were collected, counted and assessed for viability. In Experiment 2, Holstein cows were synchronized using a protocol based on estradiol and progesterone and 7 d post-estrus cows with a CL were implanted with a fertilized embryo (n = 1147 from 657 cows). Embryos were transferred as either in vivo (fresh or frozen) or IVF (frozen only). Pregnancy was confirmed at 31 ± 3 d post-estrus. Estrous expression was monitored through a leg (Exp 1) or collar (Exp 2)-mounted activity monitor. Estrous expression was quantified using 2 parameters: 1) peak activity (maximum activity) and 2) duration (total time above threshold); both parameters were categorized using the median. Data were analyzed by ANOVA using the MIXED and GLIMMIX procedures of SAS. In Exp 1, number of follicles present at AI was not affected by estrous expression. Heifers with higher peak activity had a higher number of total embryos (10.2 ± 1.2 vs 6.0 ± 1.3 embryos; P = 0.01) and a higher percent of those embryos were viable (53.1 ± 5.0 vs 23.4 ± 5.1%; P < 0.001). Longer duration estrus episodes had a higher percentage of viable embryos (51.2 ± 5.2 vs 25.3 ± 5.3%; P < 0.01); but, duration did not affect total embryos. In Exp 2, 89.1% of cows expressed estrus before ET. Animals expressing estrus before ET had substantially higher P/ET than those that did not (35.8 ± 1.6 vs 5.9 ± 4.9%; P < 0.001). Of the animals that expressed estrus, cows with higher estrous expression had higher ET success than those with low estrous expression (41.5 ± 2.3 vs 30.6 ± 2.2%; P < 0.001). No interaction was found between estrous expression and embryo transfer method, but IVF was found to have lower P/ET than both fresh and frozen (30 ± 1.9 vs 38.7 ± 3.6 vs 39.0 ± 3.1%; P = 0.02). In conclusion, estrous expression is important for both periods before and after ET as seen by more viable embryos and higher P/ET for animals with greater estrous expression.