The problem of the study was related to the asymptotic and relative efficiencies of the conventional biserial correlation coefficients and the two modified biserial correlation coefficients proposed by Brogden (1) and Lord-Clemans (2; 15). These were determined under some selected cutting points (p), and various sizes of samples (n) randomly drawn from the; simulated bivariate populations of four different shapes—normal, lognormal, double exponential, and the contaminated normal, and of various degrees in population parameter (p).