Laser guidance is the technique that uses a weakly convergent laser beam to trap particles radially in the center of the beam and simultaneously propel them along the beam propagation axis with a travelling distance over millimeters. In this paper, we describe the applications of laser guidance to detect different cell types, including those of phenotypically transformed or gene-modified cells, especially for situations in which fluorescent markers used in flow cytometry for cell detection are not available or their application is contraindicated by clinical restriction. The optical force, which determines the guidance speed of the cell, is dependent on the characteristics, such as size, shape, composition and refractive index, of the cell being guided. Therefore, by measuring the guidance speed of the cell along the laser beam, cells with different properties can be effectively distinguished. We report two experimental results: 1) the laser-guidance system could significantly distinguish the metastatic cancer cell type 4T1 from its non-metastatic counterpart 4T07, which could not be achieved by using a high magnification microscope; 2) The laser-guidance experiment demonstrated that only one gene modification between L-10 and TC-1 cells resulted in ~40% difference in guidance speed. These experimental data indicate that laser guidance can be used to detect subtle differences between sub-cell types.