Excess molar enthalpies (H-m,H-123 (E)), measured at (298.15, 308.15, and 318.15) K in a Calvet low-temperature microcalorimeter, are reported for the ternary mixture of p-cymene ( 1)+ alpha-pinene ( 2) + beta-pinene ( 3) at atmospheric pressure. The results serve to show that all the experimental H-m,123(E) values are positive and that they increase with an increase in temperature. In all cases, maximum values were observed in the vicinity of x(1) approximate to 0.5. Furthermore, at constant x(1), the measured H-m,123(E) values increase as the ratio of x(2)/x(3) increases.