Viability of keratinocytes of HaCaT immortalized line incubated with sodium dodecyl sulfate for 3 min, 1 and 48 h, was studied by light microscopy, MTT test, and neutral red absorption test. The IC values were determined for each of the studied lengths of exposure. HaCaT cells exhibited a dose-dependent decrease of viability under the effect of sodium dodecyl sulfate, proportional to the length of exposure. The values measured by different methods (MTT test and neutral red absorption test) varied, the differences were determined by the duration of exposure to sodium dodecyl sulfate. The dispersion of values for 1 and 48 h exposure, obtained by MTT method, was greater than of the values obtained by neutral red absorption test.