Background: The effects of job strain on helper-inducer (CD4+CD29+) T cells and suppressor-inducer (CD4+CD45RA+) T cells are not clear. Methods: The subjects were 65 male blue-collar workers in a chemical plant in Japan. Perceived job stressors were assessed using the Japanese version of Job Content Questionnaire, i.e. job demands, job control, supervisor support and coworker support. Blood samples were taken from these subjects, and number and percentage of total lymphocytes were calculated for total T cells, helper (CD4+) T cells, suppressor/cytotoxic (CD8+) T cells, helper-inducer (CD4+CD29+) T cells and suppressor-inducer (CD4+CD45RA+) T cells using the double-staining fluorescence. Results: Job control significantly and positively correlated with number and percentage of helper-inducer (CD4+CD29+) T cells, after controlling for age, number of cigarettes per day and blood lead concentration (Spearman’s partial correlation, p < 0.05), while job demands, supervisor support or coworker support did not (p > 0.05). The job strain index, i.e. the ratio of job demands to job control, significantly and negatively correlated with the percentage of helper-inducer (CD4+CD29+) T cells (p < 0.05). None of the job stress scales significantly correlated with number or percentage of suppressor-inducer (CD4+CD45RA+) T cells (p > 0.05). Conclusions: It is suggested that higher job strain or lower job control is associated with a decrease in helper-inducer (CD4+CD29+) T cells in Japanese blue-collar workers. © 1997 S. Karger AG, Basel.