The acute effects of smoking specially filtered cigarettes on the levels of pituitary, adrenal and thyroid hormones as well as C-peptide were studied. Serum GH, ACTH, TSH, T4 and C-peptide were measured before and after smoking 2 specially filtered cigarettes in 15 healthy male smokers and 11 male non-smokers. After smoking, the GH level was significantly higher in the smokers (median 5.36 mIU L-1) compared to the non-smokers (0.71 mIU L-1, p = 0.003). There was a significant increase in GH levels in the smokers after smoking (p = 0.008). No increase in GH was seen in the non-smokers. There was no significant changes in serum cortisol, T4, ACTH and C-peptide after smoking in both groups. This finding showed that despite smoking specially filtered cigarettes stimulatory effects on the GH secretion in the smokers were still evident.