Abstract. For some continued fractions Q = 60 + al/(bx + • ■ ■ ) with mth convergent Qm, it is shown that relative errors are monotone in some arguments. If all the entries a and ft; in Q are positive, then the relative error \Q",/Q -1| is bounded by \Q",/Qm+\ -1|, which is nonincreasing in the partial denominator />; for each j > 0, as is \Qm/Q -1| for j ^ m + 1.If />y > 1 for all j > 1, b0 > 0, and a}= ( -1)/ + 'c; where cy > 0 and for y even, c, < 1, then \Qm/Q ~ *l 's bounded by \Qm/Qm + i -1|, and both are nonincreasing in fy for even j ¡Í m + 2. These facts apply to continued fractions of Euler, Gauss and Laplace used in computing Poisson, binomial and normal probabilities, respectively, giving monotonicity of relative errors as functions of the variables in suitable ranges.For computation of various functions in suitable regions, continued fractions provide the current method of choice because of their speed of convergence for a given accuracy. Another advantage is that in certain cases error bounds are rather easily available at each stage, since one or two successive convergents are alternately above and below the final result. Thus, even in regions where continued fractions are less efficient than other methods, they may provide checks on the accuracy of those methods, which may lack such easy error bounds of their own. Then, monotonicity properties of the errors in some of the arguments are useful in reducing the amount of checking to be done. This note treats such monotonicity properties, specifically for Laplace and Gauss continued fractions useful in computing hypergeometric functions and thus probabilities of the gamma and beta families such as Poisson and binomial probabilities. For a different monotonicity property of continued fractions, see [9].1. Continued Fractions. A continued fraction is given by two sequences of numbers ( K} " > o and {an}n>x, and will be written as (1.1) 0 = ^0 + 7^1 bx+ b2 + In this paper all the a-and bj will be real numbers. Let Tn(z):= an/(bn + z) for any z (the symbol " := " means "equals by definition"). Then the with convergent of the continued fraction is given by Qm = bo+Tx(T2(---(Tm(0))---))