Inhibition of leucocyte migration from a capillary tube is generally regarded as an in vitro corralate of cellular immunity in many species. However, significant difficulties have been encountered in the application of this test in human subjects. An alternative to this LMIT in agarose test, in which cells migrate between the agarose layer and the glass was proposed previously. In this study the said method was used in humans and applied to purified protein derivative (PPD), streptococcus group A antigen (STA) and phytohemaglutinin (PHA) (and to several other antigens, not mentioned in this report). A good correlation was obtained between skin sensitivity and antigen induced inhibition of peripheral leucocytes for PPD in 15 healthy subjects. Inhibition of cells were noted in 19 out of 20 subjects when PHA was used. Similar findings were obtained by STA. This agarose method is technically simple and requires much fewer cells (11 x 10(6) cells per antigen) than the capillary method. It also requires very small quantities of antigen (5 microliter per 11 x 10(6) cells). Our findings suggest the suitability of LMIT in agarose gel method in the detection of cell mediated immunity in man.