In this study an attempt was made to find out the critical influence of ego-strength on the job performance-job satisfaction relationship. The E-S Scale (Ego-Strength Scale) and the S-D Employee's Inventory were administered on a sample of 200 blue-collar workers of a state owned spinning mill located in North India. The performance data were obtained with the help of daily work records of the respondents. The moderated regression and sub-group analytical strategies were applied to determine such effects. The moderated regression analysis did not show significant moderating effect (F = 1.50, df = 1,196). The sub-group analysis show negligible moderating effect which was not found to be statistically significant (CR = .35).