The software (MAPA-PC) for personal computers, designed by the author, provides precise and fast studies of ABPM, especially when comparing two anti-hypertensive treatments. It implies strict definitions of groups (e.g. dippers), indices (peak, trough, peak/trough ratio), and the type of smoothing of measured values: means (over 1, 2 or 3 hours) or smoothing by functions (polynomials or trigonometric series). The software calculates standard parameters (nighttime and daytime means, peak, trough...) as well as more original values (nighttime period from points of inflexion in the curve, slope in these points, coefficients of variation on differences between 2 ABPM of a given subject...). It uses statistical tests (Mann and Whitney's U, Pearsons chi square, Snedecor's F) to compare results of treatment. It provides many types of curves (blood pressure lines, box-plots) which show kinetics and variability of blood pressure. The user can compare various types of smoothing (e.g. 2 vs 3 harmonics in Fourier series). The software was used on 237 records of 79 patients, in a randomized trial. It was written with Turbo Pascal and works on DOS personal computers. It is interesting for epidemiologic studies or clinical trials in which ABPM are used.