The relationship between various characters of teats and milking characteristics was studied in order to see the possibility of improving teat conformation in relation to efficiency of milking in 28 Jersey cows in early period of lactation at Kozu Stock Farm. The herd has been bred in considerablly closed population.Such characters as length, diameter, tonus of sphincter muscle and size of orifice were mea- sured on teats, and such milking characteristics as maximum rate of flow, average rate of flow, milking time, peak period and yield at recorded milking were recorded. Tonus of sphincter muscle of teat was measured by applying to teat the pressing band which was the modification of that of the apparatus for blood pressure by RIVA-ROCCI, and size of teat orifice was measured by in- serting a cornical brass rod contrived by, JOHANSSON (1957).Then, coefficients of simple and multiple partial correlations with such factors as yield at recorded milking, stage of lactation and number of lactation held constant were calculated between these characters of teats and milking characteristics. Furthermore, influences of parents on phenotypic value of these characters of daughters and degree of phenotypic resemblance in half-sibs were estimated by analysis of variance of intra- and inter -class to see the role of inheritance.Results obtained here are summarized as following.(1) Significant positive correlation was present between length and diameter of teats, but not between these and tonus of sphincter muscle or size of orifice in characters of teats.(2) Significant positive correlation was present between maximum rate of flow and average rate of flow and between milking time and peak period, but highly negative correlations were present between the former two and the latter two in milking characteristics.(3) In correlations between these characters and yield, stage of lactation and number of lactation, those between tonus of sphincter muscle and yield or stage of lactation, and that between milking time and stage of lactation were all positive; those between size of teat orifice and yield or stage of lactation, and that between average rate of flow and stage of lactation were all negative.(4) Significant negative correlations were present in such combinations between characters of teats and milking characteristics as between tonus of sphincter muscle and maximum rate of flow in both simple and partial correlations, between tonus of sphincter muscle and average rate of. flow in simple correlation, between size of teat orifice and milking time in simple correlation, between size of teat orifice and peak period in partial correlation, and between teat length and milking time or peak period in partial correlation.(5) Influences of both parents or one of them were significant on such characters as following. Sire and dam: Tonus of sphincter muscle of teat Sire: Size of teat orifice, asymmetry between front and rear teat orifice, asymmetry between left and right teat orifice, teat length, asymmetry between left and right teat length, maximum rate of flow, average rate of flow, milking time and yield at recorded milking. Dam: Diameter of teats, asymmetry between front and rear teat diameter.In conclusion, the tonus of sphincter muscle had larger influence upon the maximum rate of flow than the size of teat orifice from the present data and they are fairly heritable characters.