The success in discovering ore deposits or prospects is usually attributed to regional geophysical or/and geochemical anomalies, which, even though containing only single anomalous point, should not be neglected. The adoption of dense -spacing search lines is not necessarily acceptable in that the weighing of exploration costs and the value of the targets to ce searched is indispensable. One of the problems involved in the layout of exploration strategy is the estimate of probability with which the search lines intersect geological targets of interest. Up till now, only single target with linear or elliptical shape has been dealt with. In the present paper, however, the author discusses multi-targets with arbitrary shape represented by sets of polygons, using analytical, numerical integration, and Monte Carlo methods for the comparison of results. FORTRAN programs are developed and run in an IBM-PCXT microcomputer with test examples of single and eight targets of complex shape, the Monte Carlo method may be especially applicable if uneven distribution of target orientation is expected.