The present invention relates to 3-(heteroaryl-amino)-1,2,3,4-tetrahydro-9H-carbazole derivatives of the formula (I), wherein R, R and R are as described in the description and their use as prostaglandin receptor modulators, most particularly as prostaglandin Dreceptor modulators, in the treatment of various prostaglandin-mediated diseases and disorders, to pharmaceutical compositions containing these compounds and to processes for their preparation.