The upgrading of White Fulani cattle using Friesian bulls in Vom between 1970 and 1979 was assessed. The average lactation yields of 798, 2121, 2635, 2837, and 2953 kg for White Fulani (FU), 1/2 Friesian -1/2 White Fulani (FUF1), 3/4 Friesian -1/4 White Fulani (B1), 7 /8 Friesian -1/8 White Fulani (B2) and Friesian (FR) cows, respectively, increased with an increase in Friesian contribution. The average lactation lengths also increased similarly: 169 days for FU, 260 days for F1, 275 days for B1, 286 days for B2, and 291 days for FR. The age at first calving for FU, FUF1, B1, B2, and FR born on the farm were 39, 29.5, 32.4, 33.2, and 29.4 months, respectively, while subsequent calvings occurred every 348, 342.5, 350, 364, and 372 days, respectively. This shows that most of the breeds in Vom calved almost each year. The heterosis of lactation yield, lactation length, yield per day, butterfat per cent, age at first calving, and calving interval in FUF1 were 13.1, 12.7, 12.4, 0.0, 13.8, and 5.3%, respectively. Upgrading of White Fulani cows appears to have improved milk production in Vom.