This paper reports the results of an investigation into the use of ultrasonic testing to high-strength concrete having the 28 days compressive cube strength of about 80 MPa. The parameters studied include cement type, effect of silica fume, age, and curing conditions. Normal portland cement (Type A) and normal blastfurnace portland cement (Type SA) were used in the producing the high-strength mixes. The results confirm that the compressive strength-pulse velocity relationship from an early age of 5 hours, can be represented by an exponential curve. Air-curing is identified as the major factor in reducing the pulse velocity of high-strength concrete at any age, due to strength loss and moisture loss. The use of silica fume in the concrete mixes improved the pulse velocity values through the pore filling and pozzolanic effects.of silica fume. The paste efficiency principle based on the pulse velocity difference between water-cured and air-cured test specimens can be used to evaluate the in-situ concrete strength. The results showed that the k-value relating the pulse velocity difference and the ratio of water-cured strength to air- cured (in-situ) strength is 0.010 for high-strength concrete compared to 0.019 for medium-strength concrete.