We have previously shown that bPTH-(l-34) stimulates the incorporation of 3H-myo-inositol into phosphatidylinositol in fetal rat limb bones (Rappaport and Stern, 1986). The current studies were undertaken to determine whether the hormone would also show effects on the production of inositol phosphates. We have compared the effects of bPTH-(l-34) with those of Nleu8,18Tyr34-bPTH-(3-34)amide, a PTH analog shown to be without effects on cyclic AMP in renal (Rosenblatt, et al., 1977) or osseous (Goldring, et al., 1985, Hermann-Erlee, et al., 1983) tissue. In addition, we have examined the effects of α-thrombin, which stimulates resorption in fetal rat limb bones (Hoffmann, et al., 1986) and which increases production of inositol phosphates in several tissues (Rendu et al., 1983, Carney, et al. 1985).