We evaluated serum concentrations of two early and sensitive markers of immune activation, interleukin-2 receptor (sIL-2R) and intercellular adhesion molecule-1 (ICAM-1) in two age-matched groups of in-vitro fertilization (IVF)-embryo transfer women, group I (n = 26) without and group II (n = 40) with methylprednisolone (MPD) supplementation of the luteal phase, on the days of oocyte retrieval (sample A) and embryo transfer (B), and second (C) and 13th (D) days post-transfer and in 20 normally cycling women (controls) on the day of luteinizing hormone (LH) peak. No difference in the outcome of the IVF-embryo transfer was observed between groups I and II. In sample A, both immunomarker concentrations showed no significant difference between the two groups of IVF women, while they were significantly higher (P < 0.01) than values in controls. In cycles in which conception occurred, significantly higher immunomarker concentrations were observed in sample A of both groups I and II compared with those in unsuccessful cycles of the same group. A significant decrease of both sIL-2R and ICAM-1 was noticed in sample B only in group II (P < 0.0001 and P < 0.001 respectively; paired t-test) that continued further in the late luteal phase only in the case of conception, independently of MPD supplementation. These data suggest that (i) due to multiple ovulations, IVF-embryo transfer women show elevated concentrations of sIL-2R and ICAM-1 at oocyte retrieval; (ii) since, even at oocyte retrieval stage, high concentrations of immunomarkers are associated with IVF-embryo transfer success, sIL-2R and ICAM-1 could be used as early indicators for conception cycles; (iii) transient suppression of T cell activity by MPD supplementation following IVF-embryo transfer does not improve pregnancy rate.