The correlation of CPT resistance and undrained shear strength of soft Holocene clays is discussed in this paper. This soil type, covering significant part of Hungary is frequently involved in different geotechnical engineering problems such as building of highway embankments. Soil samples of eight different sites have been studied, samples were taken at each site and cone penetration tests were performed. The samples were tested by means of unconfined compression and consolidatedundrained triaxial compression tests. The correlation of the determined undrained shear strength and the experienced CPT results was evaluated and the empirical cone factors ( N k , N kt , N ke , N Δu ) were determined for each tests. The back-calculated cone factors have been compared with the values suggested by earlier works in this field. The possible correlations between cone factors and different soil properties (such as index of plasticity, pore pressure coefficient etc.) are also discussed in the paper and recommendations are given for estimation of undrained shear strength of Holocene clays.