Three computer programs in Fortran 77 are presented to calculate the gravity anomalies of 2.5-D and 2-D bodies with either constant density contrast or linear decrease of density contrast with depth or a second order decrease of density contrast with depth. The decrease of density contrast in sedimentary basins may be approximated by a quadratic function. A sedimentary basin may be viewed as a number of 2-D or 2.5-D prisms placed in juxtaposition. Approximate equations for both cases are developed for rapid calculation of gravity anomalies. Efficient methods are developed for two-and-half and two-dimensional analysis of gravity anomalies by an appropriate use of the exact and approximate equations. The depths to the basement are adjusted iteratively by comparing the calculated anomalies with the observed anomalies. A computer program is also developed to deduce the s tructure of a sedimentary basin along any off-set profile by a suitable modification of the anomaly equations. By interpreting several off-set profiles covering the entire basin, a depth contour map can be drawn which is comparable to a structural map deduced by 3-D methods. Two field examples are given demonstrating the utility of the computer programs.