Our objective was to investigate the effect of extending the duration of the voluntary waiting period (VWP) on reproductive performance of lactating dairy cows. Holstein cows [n = 1,082; 434 primiparous (PP) and 648 multiparous (MP)] from 3 commercial dairy farms in New York were blocked by parity and total milk production in their previous lactation (MP only) and were randomly assigned to receive first timed AI (TAI) service at 60 ± 3 (SVWP) or 88 ± 3 DIM (LVWP) after synchronization of ovulation with the Double-Ovsynch protocol (GnRH-7 d-PGF-3 d-GnRH-7 d- GnRH-7 d-PGF-56 h-GnRH-16 h-TAI). Pregnancy diagnosis was conducted by rectal palpation or transrectal ultrasound 39 and 90 d after AI. Data for pregnancies per AI (P/AI) at 39 d after TAI, pregnancy loss (PL) from 39 to 90 d after AI, and percentage of cows pregnant up to 150 DIM were analyzed by logistical regression using PROC GLIMMIX of SAS. Models included the effect of treatment, parity, and their interaction. Farm was included as a random effect in all models. At 39 d after TAI, P/AI were greater (P < 0.01) for cows in the LVWP (46.0%; 228/496) than cows in the SVWP (38.4%; 225/586) group. Pregnancies per AI were greater (P < 0.01) for PP (49.5%; 215/434) than for MP (36.7; 238/648) cows. Pregnancy loss, was similar (P = 0.88) for cows in the LVWP (4.5%) and the SVWP (4.7%) group, and for PP (4.6%) and MP (4.6%) cows (P = 0.97). The percentage of cows pregnant by 150 DIM was similar (P = 0.23) for cows in the LVWP (62.6%; 278/444) and the SVWP (69.6%; 261/375) group but were greater (P < 0.01) for PP (74.5%; 222/298) than for MP (62.6%; 278/444) cows. The interaction between treatment and parity group did not affect (P > 0.05) P/AI, PL, or percent pregnant by 150 DIM. We conclude that extending the duration of the VWP from 60 to 88 DIM for cows receiving TAI after synchronization with the Double-Ovsynch protocol increased overall P/AI. Also, the initial differences in P/AI after first service were compensated by earlier re-insemination of cows in the SVWP group. Supported by New York Farm Viability Institute project AOR13006.